Requirements=nnbd-strong added to NNBD tests
diff --git a/LanguageFeatures/nnbd/exports_A01_t01.dart b/LanguageFeatures/nnbd/exports_A01_t01.dart
index 75164a8..4bfd347 100644
--- a/LanguageFeatures/nnbd/exports_A01_t01.dart
+++ b/LanguageFeatures/nnbd/exports_A01_t01.dart
@@ -12,6 +12,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 
 import "exports_legacy_A01_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/exports_A02_t01.dart b/LanguageFeatures/nnbd/exports_A02_t01.dart
index 2e4ddb6..4ef72f8 100644
--- a/LanguageFeatures/nnbd/exports_A02_t01.dart
+++ b/LanguageFeatures/nnbd/exports_A02_t01.dart
@@ -11,6 +11,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 
 export "legacy_lib.dart";
 //      ^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/LanguageFeatures/nnbd/exports_legacy_A01_lib.dart b/LanguageFeatures/nnbd/exports_legacy_A01_lib.dart
index f44ef7d..fbf4fff 100644
--- a/LanguageFeatures/nnbd/exports_legacy_A01_lib.dart
+++ b/LanguageFeatures/nnbd/exports_legacy_A01_lib.dart
@@ -7,7 +7,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 library export_opted_lib;
 export "opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/generics_A01_t01.dart b/LanguageFeatures/nnbd/generics_A01_t01.dart
index 5d5f59c..53a635e 100644
--- a/LanguageFeatures/nnbd/generics_A01_t01.dart
+++ b/LanguageFeatures/nnbd/generics_A01_t01.dart
@@ -11,6 +11,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 
 import "../../Utils/expect.dart";
 
diff --git a/LanguageFeatures/nnbd/generics_A01_t02.dart b/LanguageFeatures/nnbd/generics_A01_t02.dart
index eb1bcfd..83608e5 100644
--- a/LanguageFeatures/nnbd/generics_A01_t02.dart
+++ b/LanguageFeatures/nnbd/generics_A01_t02.dart
@@ -11,6 +11,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 
 import "../../Utils/expect.dart";
 
diff --git a/LanguageFeatures/nnbd/generics_A01_t03.dart b/LanguageFeatures/nnbd/generics_A01_t03.dart
index f7c5110..1d779c5 100644
--- a/LanguageFeatures/nnbd/generics_A01_t03.dart
+++ b/LanguageFeatures/nnbd/generics_A01_t03.dart
@@ -11,6 +11,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
+// Requirements=nnbd-strong
 
 import "../../Utils/expect.dart";
 
diff --git a/LanguageFeatures/nnbd/generics_A01_t04.dart b/LanguageFeatures/nnbd/generics_A01_t04.dart
index 063937e..01f39e4 100644
--- a/LanguageFeatures/nnbd/generics_A01_t04.dart
+++ b/LanguageFeatures/nnbd/generics_A01_t04.dart
@@ -11,6 +11,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
+// Requirements=nnbd-strong
 
 import "../../Utils/expect.dart";
 
diff --git a/LanguageFeatures/nnbd/generics_A01_t05.dart b/LanguageFeatures/nnbd/generics_A01_t05.dart
index f62edb8..4a654c0 100644
--- a/LanguageFeatures/nnbd/generics_A01_t05.dart
+++ b/LanguageFeatures/nnbd/generics_A01_t05.dart
@@ -11,6 +11,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 
 import "../../Utils/expect.dart";
 
diff --git a/LanguageFeatures/nnbd/generics_A01_t06.dart b/LanguageFeatures/nnbd/generics_A01_t06.dart
index 304ed4c..7464661 100644
--- a/LanguageFeatures/nnbd/generics_A01_t06.dart
+++ b/LanguageFeatures/nnbd/generics_A01_t06.dart
@@ -11,6 +11,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 
 import "../../Utils/expect.dart";
 
diff --git a/LanguageFeatures/nnbd/generics_A01_t07.dart b/LanguageFeatures/nnbd/generics_A01_t07.dart
index 73791f2..6189e56 100644
--- a/LanguageFeatures/nnbd/generics_A01_t07.dart
+++ b/LanguageFeatures/nnbd/generics_A01_t07.dart
@@ -11,6 +11,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+ // Requirements=nnbd-strong
 
 import "../../Utils/expect.dart";
 
diff --git a/LanguageFeatures/nnbd/generics_A01_t08.dart b/LanguageFeatures/nnbd/generics_A01_t08.dart
index 0f68179..5fe790b 100644
--- a/LanguageFeatures/nnbd/generics_A01_t08.dart
+++ b/LanguageFeatures/nnbd/generics_A01_t08.dart
@@ -11,6 +11,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+ // Requirements=nnbd-strong
 
 import "../../Utils/expect.dart";
 
diff --git a/LanguageFeatures/nnbd/generics_A01_t09.dart b/LanguageFeatures/nnbd/generics_A01_t09.dart
index 93cb493..15ad0ea 100644
--- a/LanguageFeatures/nnbd/generics_A01_t09.dart
+++ b/LanguageFeatures/nnbd/generics_A01_t09.dart
@@ -11,6 +11,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+ // Requirements=nnbd-strong
 
 import "../../Utils/expect.dart";
 
diff --git a/LanguageFeatures/nnbd/import_legacy_lib_A01_t01.dart b/LanguageFeatures/nnbd/import_legacy_lib_A01_t01.dart
index a64b60f..192fa03 100644
--- a/LanguageFeatures/nnbd/import_legacy_lib_A01_t01.dart
+++ b/LanguageFeatures/nnbd/import_legacy_lib_A01_t01.dart
@@ -16,6 +16,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "legacy_lib.dart";
 
 main() {
diff --git a/LanguageFeatures/nnbd/import_legacy_lib_A01_t02.dart b/LanguageFeatures/nnbd/import_legacy_lib_A01_t02.dart
index c3899e5..8d678b5 100644
--- a/LanguageFeatures/nnbd/import_legacy_lib_A01_t02.dart
+++ b/LanguageFeatures/nnbd/import_legacy_lib_A01_t02.dart
@@ -17,6 +17,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "legacy_lib.dart";
 
 main() {
diff --git a/LanguageFeatures/nnbd/import_legacy_lib_A01_t03.dart b/LanguageFeatures/nnbd/import_legacy_lib_A01_t03.dart
index 21081e2..ed3cc66 100644
--- a/LanguageFeatures/nnbd/import_legacy_lib_A01_t03.dart
+++ b/LanguageFeatures/nnbd/import_legacy_lib_A01_t03.dart
@@ -17,6 +17,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "legacy_lib.dart";
 
 main() {
diff --git a/LanguageFeatures/nnbd/import_legacy_lib_A01_t04.dart b/LanguageFeatures/nnbd/import_legacy_lib_A01_t04.dart
index 3bb9f0c..e4042d7 100644
--- a/LanguageFeatures/nnbd/import_legacy_lib_A01_t04.dart
+++ b/LanguageFeatures/nnbd/import_legacy_lib_A01_t04.dart
@@ -17,6 +17,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "legacy_lib.dart";
 
 class B extends A {
diff --git a/LanguageFeatures/nnbd/import_legacy_lib_A01_t05.dart b/LanguageFeatures/nnbd/import_legacy_lib_A01_t05.dart
index 7276a5b..87d3cea 100644
--- a/LanguageFeatures/nnbd/import_legacy_lib_A01_t05.dart
+++ b/LanguageFeatures/nnbd/import_legacy_lib_A01_t05.dart
@@ -17,6 +17,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "legacy_lib.dart";
 
 class B extends A {
diff --git a/LanguageFeatures/nnbd/import_legacy_lib_A01_t06.dart b/LanguageFeatures/nnbd/import_legacy_lib_A01_t06.dart
index 5b068de..0d0fadc 100644
--- a/LanguageFeatures/nnbd/import_legacy_lib_A01_t06.dart
+++ b/LanguageFeatures/nnbd/import_legacy_lib_A01_t06.dart
@@ -16,6 +16,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "legacy_lib.dart";
 
 class B extends A with Mx {}
diff --git a/LanguageFeatures/nnbd/import_legacy_lib_A01_t07.dart b/LanguageFeatures/nnbd/import_legacy_lib_A01_t07.dart
index f5aa7f5..39973d2 100644
--- a/LanguageFeatures/nnbd/import_legacy_lib_A01_t07.dart
+++ b/LanguageFeatures/nnbd/import_legacy_lib_A01_t07.dart
@@ -16,6 +16,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "legacy_lib.dart";
 
 class B extends A with Mx {
diff --git a/LanguageFeatures/nnbd/import_legacy_lib_A01_t08.dart b/LanguageFeatures/nnbd/import_legacy_lib_A01_t08.dart
index 9db4743..3378b49 100644
--- a/LanguageFeatures/nnbd/import_legacy_lib_A01_t08.dart
+++ b/LanguageFeatures/nnbd/import_legacy_lib_A01_t08.dart
@@ -16,6 +16,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "legacy_lib.dart";
 
 class B extends A with Mx {
diff --git a/LanguageFeatures/nnbd/import_legacy_lib_A01_t09.dart b/LanguageFeatures/nnbd/import_legacy_lib_A01_t09.dart
index 410fca4..1a120c1 100644
--- a/LanguageFeatures/nnbd/import_legacy_lib_A01_t09.dart
+++ b/LanguageFeatures/nnbd/import_legacy_lib_A01_t09.dart
@@ -16,6 +16,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "legacy_lib.dart";
 
 class MyMx {
diff --git a/LanguageFeatures/nnbd/import_legacy_lib_A01_t10.dart b/LanguageFeatures/nnbd/import_legacy_lib_A01_t10.dart
index f693f13..e7047be 100644
--- a/LanguageFeatures/nnbd/import_legacy_lib_A01_t10.dart
+++ b/LanguageFeatures/nnbd/import_legacy_lib_A01_t10.dart
@@ -16,6 +16,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "legacy_lib.dart";
 
 class B extends A with Mxn {
diff --git a/LanguageFeatures/nnbd/import_legacy_lib_A02_t01.dart b/LanguageFeatures/nnbd/import_legacy_lib_A02_t01.dart
index be63a99..e722e97 100644
--- a/LanguageFeatures/nnbd/import_legacy_lib_A02_t01.dart
+++ b/LanguageFeatures/nnbd/import_legacy_lib_A02_t01.dart
@@ -17,6 +17,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "legacy_lib.dart";
 
 main() {
diff --git a/LanguageFeatures/nnbd/legacy_lib.dart b/LanguageFeatures/nnbd/legacy_lib.dart
index c4f8d72..eb37e73 100644
--- a/LanguageFeatures/nnbd/legacy_lib.dart
+++ b/LanguageFeatures/nnbd/legacy_lib.dart
@@ -6,7 +6,7 @@
 /**
  * @author sgrekhov@unipro.ru
  */
-// @dart=2.4
+// @dart=2.6
 // SharedOptions=--enable-experiment=non-nullable
 library legacy_library_lib;
 
diff --git a/LanguageFeatures/nnbd/legacy_libraries_A01_t01.dart b/LanguageFeatures/nnbd/legacy_libraries_A01_t01.dart
index fe109bb..97994eb 100644
--- a/LanguageFeatures/nnbd/legacy_libraries_A01_t01.dart
+++ b/LanguageFeatures/nnbd/legacy_libraries_A01_t01.dart
@@ -15,7 +15,7 @@
  * treated as T
  * @author sgrekhov@unipro.ru
  */
-// @dart=2.4
+// @dart=2.6
 // SharedOptions=--enable-experiment=non-nullable
 import "../../Utils/expect.dart";
 import "opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/legacy_libraries_A01_t02.dart b/LanguageFeatures/nnbd/legacy_libraries_A01_t02.dart
index b2c2418..90c78eb 100644
--- a/LanguageFeatures/nnbd/legacy_libraries_A01_t02.dart
+++ b/LanguageFeatures/nnbd/legacy_libraries_A01_t02.dart
@@ -15,7 +15,7 @@
  * treated as T
  * @author sgrekhov@unipro.ru
  */
-// @dart=2.4
+// @dart=2.6
 // SharedOptions=--enable-experiment=non-nullable
 import "../../Utils/expect.dart";
 import "opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/legacy_libraries_A01_t03.dart b/LanguageFeatures/nnbd/legacy_libraries_A01_t03.dart
index 8f9ed27..30009a5 100644
--- a/LanguageFeatures/nnbd/legacy_libraries_A01_t03.dart
+++ b/LanguageFeatures/nnbd/legacy_libraries_A01_t03.dart
@@ -15,7 +15,7 @@
  * treated as T
  * @author sgrekhov@unipro.ru
  */
-// @dart=2.4
+// @dart=2.6
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
 import "../../Utils/expect.dart";
 import "opted_in_aliases_lib.dart";
diff --git a/LanguageFeatures/nnbd/legacy_libraries_A01_t04.dart b/LanguageFeatures/nnbd/legacy_libraries_A01_t04.dart
index 66594f7..fe940aa 100644
--- a/LanguageFeatures/nnbd/legacy_libraries_A01_t04.dart
+++ b/LanguageFeatures/nnbd/legacy_libraries_A01_t04.dart
@@ -15,7 +15,7 @@
  * treated as T
  * @author sgrekhov@unipro.ru
  */
-// @dart=2.4
+// @dart=2.6
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
 import "../../Utils/expect.dart";
 import "opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/legacy_libraries_A02_t01.dart b/LanguageFeatures/nnbd/legacy_libraries_A02_t01.dart
index 7369db2..8ce0385 100644
--- a/LanguageFeatures/nnbd/legacy_libraries_A02_t01.dart
+++ b/LanguageFeatures/nnbd/legacy_libraries_A02_t01.dart
@@ -15,7 +15,7 @@
  * named parameters.
  * @author sgrekhov@unipro.ru
  */
-// @dart=2.4
+// @dart=2.6
 // SharedOptions=--enable-experiment=non-nullable
 import "opted_in_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/legacy_libraries_A03_t01.dart b/LanguageFeatures/nnbd/legacy_libraries_A03_t01.dart
index 7a9be44..5047f7b 100644
--- a/LanguageFeatures/nnbd/legacy_libraries_A03_t01.dart
+++ b/LanguageFeatures/nnbd/legacy_libraries_A03_t01.dart
@@ -14,7 +14,7 @@
  * @description Check that the type Never is treated as the type Null
  * @author sgrekhov@unipro.ru
  */
-// @dart=2.4
+// @dart=2.6
 // SharedOptions=--enable-experiment=non-nullable
 import "../../Utils/expect.dart";
 import "opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/legacy_libraries_A03_t02.dart b/LanguageFeatures/nnbd/legacy_libraries_A03_t02.dart
index eb98abf..4f04ffa 100644
--- a/LanguageFeatures/nnbd/legacy_libraries_A03_t02.dart
+++ b/LanguageFeatures/nnbd/legacy_libraries_A03_t02.dart
@@ -14,7 +14,7 @@
  * @description Check that the type Never is treated as the type Null
  * @author sgrekhov@unipro.ru
  */
-// @dart=2.4
+// @dart=2.6
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
 import "../../Utils/expect.dart";
 import "opted_in_aliases_lib.dart";
diff --git a/LanguageFeatures/nnbd/legacy_libraries_A04_t01.dart b/LanguageFeatures/nnbd/legacy_libraries_A04_t01.dart
index 81bf835..b78b316 100644
--- a/LanguageFeatures/nnbd/legacy_libraries_A04_t01.dart
+++ b/LanguageFeatures/nnbd/legacy_libraries_A04_t01.dart
@@ -11,7 +11,7 @@
  * pre-NNBD legacy library
  * @author sgrekhov@unipro.ru
  */
-// @dart=2.4
+// @dart=2.6
 // SharedOptions=--enable-experiment=non-nullable
 
 class A {}
diff --git a/LanguageFeatures/nnbd/legacy_libraries_A04_t02.dart b/LanguageFeatures/nnbd/legacy_libraries_A04_t02.dart
index de6fc18..1d2c2eb 100644
--- a/LanguageFeatures/nnbd/legacy_libraries_A04_t02.dart
+++ b/LanguageFeatures/nnbd/legacy_libraries_A04_t02.dart
@@ -11,7 +11,7 @@
  * pre-NNBD legacy library
  * @author sgrekhov@unipro.ru
  */
-// @dart=2.4
+// @dart=2.6
 // SharedOptions=--enable-experiment=non-nullable
 
 class A {}
diff --git a/LanguageFeatures/nnbd/legacy_libraries_A04_t03.dart b/LanguageFeatures/nnbd/legacy_libraries_A04_t03.dart
index a47b9db..75c0ad8 100644
--- a/LanguageFeatures/nnbd/legacy_libraries_A04_t03.dart
+++ b/LanguageFeatures/nnbd/legacy_libraries_A04_t03.dart
@@ -11,7 +11,7 @@
  * pre-NNBD legacy library
  * @author sgrekhov@unipro.ru
  */
-// @dart=2.4
+// @dart=2.6
 // SharedOptions=--enable-experiment=non-nullable
 
 class A {}
diff --git a/LanguageFeatures/nnbd/legacy_libraries_A04_t04.dart b/LanguageFeatures/nnbd/legacy_libraries_A04_t04.dart
index f647a6c..d315895 100644
--- a/LanguageFeatures/nnbd/legacy_libraries_A04_t04.dart
+++ b/LanguageFeatures/nnbd/legacy_libraries_A04_t04.dart
@@ -11,7 +11,7 @@
  * pre-NNBD legacy library
  * @author sgrekhov@unipro.ru
  */
-// @dart=2.4
+// @dart=2.6
 // SharedOptions=--enable-experiment=non-nullable
 
 class C {
diff --git a/LanguageFeatures/nnbd/legacy_libraries_A04_t05.dart b/LanguageFeatures/nnbd/legacy_libraries_A04_t05.dart
index 1167ef1..73af0b0 100644
--- a/LanguageFeatures/nnbd/legacy_libraries_A04_t05.dart
+++ b/LanguageFeatures/nnbd/legacy_libraries_A04_t05.dart
@@ -11,7 +11,7 @@
  * pre-NNBD legacy library
  * @author sgrekhov@unipro.ru
  */
-// @dart=2.4
+// @dart=2.6
 // SharedOptions=--enable-experiment=non-nullable
 
 foo({required String named}) {}
diff --git a/LanguageFeatures/nnbd/legacy_libraries_A04_t06.dart b/LanguageFeatures/nnbd/legacy_libraries_A04_t06.dart
index e260aa8..f114221 100644
--- a/LanguageFeatures/nnbd/legacy_libraries_A04_t06.dart
+++ b/LanguageFeatures/nnbd/legacy_libraries_A04_t06.dart
@@ -11,7 +11,7 @@
  * pre-NNBD legacy library
  * @author sgrekhov@unipro.ru
  */
-// @dart=2.4
+// @dart=2.6
 // SharedOptions=--enable-experiment=non-nullable
 
 class C {
diff --git a/LanguageFeatures/nnbd/legacy_library_aliases_lib.dart b/LanguageFeatures/nnbd/legacy_library_aliases_lib.dart
index f5d7c48..32dd794 100644
--- a/LanguageFeatures/nnbd/legacy_library_aliases_lib.dart
+++ b/LanguageFeatures/nnbd/legacy_library_aliases_lib.dart
@@ -6,7 +6,7 @@
 /**
  * @author sgrekhov@unipro.ru
  */
-// @dart=2.4
+// @dart=2.6
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
 library legacy_library_aliases_lib;
 
diff --git a/LanguageFeatures/nnbd/list_length_t01.dart b/LanguageFeatures/nnbd/list_length_t01.dart
index 4f50f4f..b84f44b 100644
--- a/LanguageFeatures/nnbd/list_length_t01.dart
+++ b/LanguageFeatures/nnbd/list_length_t01.dart
@@ -14,6 +14,7 @@
  * @issue 39777
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 
diff --git a/LanguageFeatures/nnbd/list_length_t02.dart b/LanguageFeatures/nnbd/list_length_t02.dart
index f51d909..ee93c6c 100644
--- a/LanguageFeatures/nnbd/list_length_t02.dart
+++ b/LanguageFeatures/nnbd/list_length_t02.dart
@@ -14,6 +14,7 @@
  * @issue 39777
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "legacy_lib.dart";
 import "dart:async";
 import "../../Utils/expect.dart";
diff --git a/LanguageFeatures/nnbd/list_length_t03.dart b/LanguageFeatures/nnbd/list_length_t03.dart
index 8ac5d9b..e77502c 100644
--- a/LanguageFeatures/nnbd/list_length_t03.dart
+++ b/LanguageFeatures/nnbd/list_length_t03.dart
@@ -13,6 +13,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 
diff --git a/LanguageFeatures/nnbd/list_length_t04.dart b/LanguageFeatures/nnbd/list_length_t04.dart
index ef25a07..b0c32d4 100644
--- a/LanguageFeatures/nnbd/list_length_t04.dart
+++ b/LanguageFeatures/nnbd/list_length_t04.dart
@@ -13,6 +13,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "legacy_lib.dart";
 import "dart:async";
 import "../../Utils/expect.dart";
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A01_t01.dart b/LanguageFeatures/nnbd/null_aware_operator_A01_t01.dart
index bd1857f..f42c17d 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A01_t01.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A01_t01.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A01_t02.dart b/LanguageFeatures/nnbd/null_aware_operator_A01_t02.dart
index 1393f11..59324b7 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A01_t02.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A01_t02.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A01_t03.dart b/LanguageFeatures/nnbd/null_aware_operator_A01_t03.dart
index 76b419f..4d5586f 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A01_t03.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A01_t03.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A01_t04.dart b/LanguageFeatures/nnbd/null_aware_operator_A01_t04.dart
index 7ebbfad..14327f3 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A01_t04.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A01_t04.dart
@@ -13,6 +13,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A01_t05.dart b/LanguageFeatures/nnbd/null_aware_operator_A01_t05.dart
index 9a96773..73e694c 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A01_t05.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A01_t05.dart
@@ -13,6 +13,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A02_t01.dart b/LanguageFeatures/nnbd/null_aware_operator_A02_t01.dart
index 32ad7b9..72fd1ef 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A02_t01.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A02_t01.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A02_t02.dart b/LanguageFeatures/nnbd/null_aware_operator_A02_t02.dart
index 24e5451..78c4e74 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A02_t02.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A02_t02.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A02_t03.dart b/LanguageFeatures/nnbd/null_aware_operator_A02_t03.dart
index 01118f2..31ddba4 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A02_t03.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A02_t03.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A03_t01.dart b/LanguageFeatures/nnbd/null_aware_operator_A03_t01.dart
index 2f2c0af..a110ab6 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A03_t01.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A03_t01.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A03_t02.dart b/LanguageFeatures/nnbd/null_aware_operator_A03_t02.dart
index 7af9fc8..c41999e 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A03_t02.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A03_t02.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A03_t03.dart b/LanguageFeatures/nnbd/null_aware_operator_A03_t03.dart
index 666ee18..c2b57ef 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A03_t03.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A03_t03.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A03_t04.dart b/LanguageFeatures/nnbd/null_aware_operator_A03_t04.dart
index 656f8db..fb8dc59 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A03_t04.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A03_t04.dart
@@ -13,6 +13,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A03_t05.dart b/LanguageFeatures/nnbd/null_aware_operator_A03_t05.dart
index 2f28382..d0fd360 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A03_t05.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A03_t05.dart
@@ -13,6 +13,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A04_t01.dart b/LanguageFeatures/nnbd/null_aware_operator_A04_t01.dart
index 6e6af0c..cae63ec 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A04_t01.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A04_t01.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A04_t02.dart b/LanguageFeatures/nnbd/null_aware_operator_A04_t02.dart
index 1bfd58b..d2d486d 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A04_t02.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A04_t02.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A04_t03.dart b/LanguageFeatures/nnbd/null_aware_operator_A04_t03.dart
index 669689a..8f38c97 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A04_t03.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A04_t03.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A05_t01.dart b/LanguageFeatures/nnbd/null_aware_operator_A05_t01.dart
index a875e7f..e2d3fcd 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A05_t01.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A05_t01.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 typedef String Func();
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A05_t02.dart b/LanguageFeatures/nnbd/null_aware_operator_A05_t02.dart
index 39bcc95..1c6d600 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A05_t02.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A05_t02.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,extension-methods
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 extension Tricky on int {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A06_t01.dart b/LanguageFeatures/nnbd/null_aware_operator_A06_t01.dart
index 8c39f54..465e7c6 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A06_t01.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A06_t01.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A06_t02.dart b/LanguageFeatures/nnbd/null_aware_operator_A06_t02.dart
index 3f064d4..2d45288 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A06_t02.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A06_t02.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A06_t03.dart b/LanguageFeatures/nnbd/null_aware_operator_A06_t03.dart
index fd56269..56526e9 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A06_t03.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A06_t03.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A07_t01.dart b/LanguageFeatures/nnbd/null_aware_operator_A07_t01.dart
index 65b5de6..82b1db5 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A07_t01.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A07_t01.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A07_t02.dart b/LanguageFeatures/nnbd/null_aware_operator_A07_t02.dart
index 2d019f1..9c064ee 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A07_t02.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A07_t02.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A07_t03.dart b/LanguageFeatures/nnbd/null_aware_operator_A07_t03.dart
index 243e570..bdd75f4 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A07_t03.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A07_t03.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A08_t01.dart b/LanguageFeatures/nnbd/null_aware_operator_A08_t01.dart
index 4437439..a3e3a98 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A08_t01.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A08_t01.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A08_t02.dart b/LanguageFeatures/nnbd/null_aware_operator_A08_t02.dart
index 886608d..d8557e5 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A08_t02.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A08_t02.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A08_t03.dart b/LanguageFeatures/nnbd/null_aware_operator_A08_t03.dart
index 9365d56..87204d4 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A08_t03.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A08_t03.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A09_t01.dart b/LanguageFeatures/nnbd/null_aware_operator_A09_t01.dart
index 044968e..4938531 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A09_t01.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A09_t01.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A09_t02.dart b/LanguageFeatures/nnbd/null_aware_operator_A09_t02.dart
index 00715de..d638813 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A09_t02.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A09_t02.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A09_t03.dart b/LanguageFeatures/nnbd/null_aware_operator_A09_t03.dart
index 415e7a3..f171c5b 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A09_t03.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A09_t03.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A09_t04.dart b/LanguageFeatures/nnbd/null_aware_operator_A09_t04.dart
index 763cca6..c93fece 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A09_t04.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A09_t04.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A09_t05.dart b/LanguageFeatures/nnbd/null_aware_operator_A09_t05.dart
index 0fea3f3..44a0537 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A09_t05.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A09_t05.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A09_t06.dart b/LanguageFeatures/nnbd/null_aware_operator_A09_t06.dart
index eee0a2e..cc2ff61 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A09_t06.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A09_t06.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A09_t07.dart b/LanguageFeatures/nnbd/null_aware_operator_A09_t07.dart
index f5b9933..7c4becf 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A09_t07.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A09_t07.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A09_t08.dart b/LanguageFeatures/nnbd/null_aware_operator_A09_t08.dart
index ebe2ce5..cbff20f 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A09_t08.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A09_t08.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A09_t09.dart b/LanguageFeatures/nnbd/null_aware_operator_A09_t09.dart
index ffbcff3..0ac78c1 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A09_t09.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A09_t09.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A09_t10.dart b/LanguageFeatures/nnbd/null_aware_operator_A09_t10.dart
index 6e27998..f6117d4 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A09_t10.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A09_t10.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A09_t11.dart b/LanguageFeatures/nnbd/null_aware_operator_A09_t11.dart
index 7f03d50..ec0b141 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A09_t11.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A09_t11.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A09_t12.dart b/LanguageFeatures/nnbd/null_aware_operator_A09_t12.dart
index e295421..70eed8b 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A09_t12.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A09_t12.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,triple-shift
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A09_t13.dart b/LanguageFeatures/nnbd/null_aware_operator_A09_t13.dart
index acf041a..1c2dc28 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A09_t13.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A09_t13.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A10_t01.dart b/LanguageFeatures/nnbd/null_aware_operator_A10_t01.dart
index 8fdfc5a..4a426dd 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A10_t01.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A10_t01.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A10_t02.dart b/LanguageFeatures/nnbd/null_aware_operator_A10_t02.dart
index c7d831f..d6c82ed 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A10_t02.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A10_t02.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A10_t03.dart b/LanguageFeatures/nnbd/null_aware_operator_A10_t03.dart
index 1431b10..3ede493 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A10_t03.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A10_t03.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A11_t01.dart b/LanguageFeatures/nnbd/null_aware_operator_A11_t01.dart
index e1f1878..974072a 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A11_t01.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A11_t01.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A11_t02.dart b/LanguageFeatures/nnbd/null_aware_operator_A11_t02.dart
index b79066f..bc42c41 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A11_t02.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A11_t02.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A11_t03.dart b/LanguageFeatures/nnbd/null_aware_operator_A11_t03.dart
index 599fd64..9c5f9aa 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A11_t03.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A11_t03.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A11_t04.dart b/LanguageFeatures/nnbd/null_aware_operator_A11_t04.dart
index 6ac75e3..3d36b30 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A11_t04.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A11_t04.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A11_t05.dart b/LanguageFeatures/nnbd/null_aware_operator_A11_t05.dart
index 6fde4f7..59c7754 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A11_t05.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A11_t05.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A11_t06.dart b/LanguageFeatures/nnbd/null_aware_operator_A11_t06.dart
index cb1a85f..a74b9f5 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A11_t06.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A11_t06.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A11_t07.dart b/LanguageFeatures/nnbd/null_aware_operator_A11_t07.dart
index ac0626a..6829ec0 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A11_t07.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A11_t07.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A11_t08.dart b/LanguageFeatures/nnbd/null_aware_operator_A11_t08.dart
index a9d7d26..53c03e6 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A11_t08.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A11_t08.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A11_t09.dart b/LanguageFeatures/nnbd/null_aware_operator_A11_t09.dart
index d6ed9cd..4650f4d 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A11_t09.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A11_t09.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A11_t10.dart b/LanguageFeatures/nnbd/null_aware_operator_A11_t10.dart
index 9bb824e..6b70d11 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A11_t10.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A11_t10.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A11_t11.dart b/LanguageFeatures/nnbd/null_aware_operator_A11_t11.dart
index 159575c..198cbf3 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A11_t11.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A11_t11.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A11_t12.dart b/LanguageFeatures/nnbd/null_aware_operator_A11_t12.dart
index 485749f..cbd5e5e 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A11_t12.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A11_t12.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,triple-shift
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A11_t13.dart b/LanguageFeatures/nnbd/null_aware_operator_A11_t13.dart
index 9805399..4c9865b 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A11_t13.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A11_t13.dart
@@ -16,6 +16,7 @@
  * @issue 39714
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A12_t01.dart b/LanguageFeatures/nnbd/null_aware_operator_A12_t01.dart
index 4582f33..fb0779f 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A12_t01.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A12_t01.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A12_t02.dart b/LanguageFeatures/nnbd/null_aware_operator_A12_t02.dart
index b6a0345..bab7261 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A12_t02.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A12_t02.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A12_t03.dart b/LanguageFeatures/nnbd/null_aware_operator_A12_t03.dart
index 1720a44..bebd3fa 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A12_t03.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A12_t03.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A13_t01.dart b/LanguageFeatures/nnbd/null_aware_operator_A13_t01.dart
index 9f0976d..dc8681d 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A13_t01.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A13_t01.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A13_t02.dart b/LanguageFeatures/nnbd/null_aware_operator_A13_t02.dart
index ceda771..4591809 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A13_t02.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A13_t02.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A13_t03.dart b/LanguageFeatures/nnbd/null_aware_operator_A13_t03.dart
index 266a51a..ceb7bc1 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A13_t03.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A13_t03.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A13_t04.dart b/LanguageFeatures/nnbd/null_aware_operator_A13_t04.dart
index cff1bf3..c656db5 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A13_t04.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A13_t04.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A13_t05.dart b/LanguageFeatures/nnbd/null_aware_operator_A13_t05.dart
index df2bc15..bcfffb3 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A13_t05.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A13_t05.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A13_t06.dart b/LanguageFeatures/nnbd/null_aware_operator_A13_t06.dart
index 2ef9351..2f47b5c 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A13_t06.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A13_t06.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A13_t07.dart b/LanguageFeatures/nnbd/null_aware_operator_A13_t07.dart
index 34fe613..3c705e8 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A13_t07.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A13_t07.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A13_t08.dart b/LanguageFeatures/nnbd/null_aware_operator_A13_t08.dart
index 512fedc..e78c656 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A13_t08.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A13_t08.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A13_t09.dart b/LanguageFeatures/nnbd/null_aware_operator_A13_t09.dart
index ca32603..4a538fb 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A13_t09.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A13_t09.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A13_t10.dart b/LanguageFeatures/nnbd/null_aware_operator_A13_t10.dart
index 4707143..ae5cac9 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A13_t10.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A13_t10.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A13_t11.dart b/LanguageFeatures/nnbd/null_aware_operator_A13_t11.dart
index b5b78bc..3f62249 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A13_t11.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A13_t11.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A13_t12.dart b/LanguageFeatures/nnbd/null_aware_operator_A13_t12.dart
index 9a48964..8fc1243 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A13_t12.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A13_t12.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,triple-shift
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A13_t13.dart b/LanguageFeatures/nnbd/null_aware_operator_A13_t13.dart
index 28818cf..ba6940e 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A13_t13.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A13_t13.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A14_t01.dart b/LanguageFeatures/nnbd/null_aware_operator_A14_t01.dart
index 0cf047e..8b2ef67 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A14_t01.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A14_t01.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A14_t02.dart b/LanguageFeatures/nnbd/null_aware_operator_A14_t02.dart
index 160c91c..42505ba 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A14_t02.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A14_t02.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A14_t03.dart b/LanguageFeatures/nnbd/null_aware_operator_A14_t03.dart
index 120ef34..d627fb7 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A14_t03.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A14_t03.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A15_t01.dart b/LanguageFeatures/nnbd/null_aware_operator_A15_t01.dart
index 4b582c9..434832b 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A15_t01.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A15_t01.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A15_t02.dart b/LanguageFeatures/nnbd/null_aware_operator_A15_t02.dart
index c75929f..7c5d86d 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A15_t02.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A15_t02.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A15_t03.dart b/LanguageFeatures/nnbd/null_aware_operator_A15_t03.dart
index d3ae47b..f1346b4 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A15_t03.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A15_t03.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A15_t04.dart b/LanguageFeatures/nnbd/null_aware_operator_A15_t04.dart
index e6cd1ff..a5ca392 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A15_t04.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A15_t04.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A15_t05.dart b/LanguageFeatures/nnbd/null_aware_operator_A15_t05.dart
index bac88f0..1fcfbb2 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A15_t05.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A15_t05.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A15_t06.dart b/LanguageFeatures/nnbd/null_aware_operator_A15_t06.dart
index a4684f2..616cbba 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A15_t06.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A15_t06.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A15_t07.dart b/LanguageFeatures/nnbd/null_aware_operator_A15_t07.dart
index ba70e5a..2b82ff1 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A15_t07.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A15_t07.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A15_t08.dart b/LanguageFeatures/nnbd/null_aware_operator_A15_t08.dart
index e28a9e0..c366006 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A15_t08.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A15_t08.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A15_t09.dart b/LanguageFeatures/nnbd/null_aware_operator_A15_t09.dart
index 480833b..75824eb 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A15_t09.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A15_t09.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A15_t10.dart b/LanguageFeatures/nnbd/null_aware_operator_A15_t10.dart
index d3cc07b..6d0bd63 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A15_t10.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A15_t10.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A15_t11.dart b/LanguageFeatures/nnbd/null_aware_operator_A15_t11.dart
index 6e72811..63e17cd 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A15_t11.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A15_t11.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A15_t12.dart b/LanguageFeatures/nnbd/null_aware_operator_A15_t12.dart
index 050fc9f..20a85ce 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A15_t12.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A15_t12.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,triple-shift
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A15_t13.dart b/LanguageFeatures/nnbd/null_aware_operator_A15_t13.dart
index 3d5cbea..ebc4d04 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A15_t13.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A15_t13.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A16_t01.dart b/LanguageFeatures/nnbd/null_aware_operator_A16_t01.dart
index 7ee2c35..1e548d8 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A16_t01.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A16_t01.dart
@@ -22,6 +22,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A16_t02.dart b/LanguageFeatures/nnbd/null_aware_operator_A16_t02.dart
index 53b8d25..aef1cf8 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A16_t02.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A16_t02.dart
@@ -23,6 +23,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A16_t03.dart b/LanguageFeatures/nnbd/null_aware_operator_A16_t03.dart
index 50bf0e1..09dc8fa 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A16_t03.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A16_t03.dart
@@ -22,6 +22,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A16_t04.dart b/LanguageFeatures/nnbd/null_aware_operator_A16_t04.dart
index b216078..e726458 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A16_t04.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A16_t04.dart
@@ -23,6 +23,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A17_t01.dart b/LanguageFeatures/nnbd/null_aware_operator_A17_t01.dart
index 2cfdc9f..3055d9c 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A17_t01.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A17_t01.dart
@@ -17,6 +17,7 @@
  * @issue 39141
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A17_t02.dart b/LanguageFeatures/nnbd/null_aware_operator_A17_t02.dart
index 9b730d9..997f4e5 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A17_t02.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A17_t02.dart
@@ -18,6 +18,7 @@
  * @issue 39141
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A17_t03.dart b/LanguageFeatures/nnbd/null_aware_operator_A17_t03.dart
index 42d96a6..bb4fb85 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A17_t03.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A17_t03.dart
@@ -17,6 +17,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A17_t04.dart b/LanguageFeatures/nnbd/null_aware_operator_A17_t04.dart
index bf36526..71a3f73 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A17_t04.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A17_t04.dart
@@ -17,6 +17,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 
 class C {
   String test1 = "Let it be";
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A17_t05.dart b/LanguageFeatures/nnbd/null_aware_operator_A17_t05.dart
index 9242c0b..50377d9 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A17_t05.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A17_t05.dart
@@ -18,7 +18,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
-import "../../Utils/expect.dart";
+// Requirements=nnbd-strong
 
 class C {
   String test1 = "Let it be";
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A17_t06.dart b/LanguageFeatures/nnbd/null_aware_operator_A17_t06.dart
index 0d516e7..c0b7f8c 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A17_t06.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A17_t06.dart
@@ -18,6 +18,7 @@
  * @issue 39141
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A17_t07.dart b/LanguageFeatures/nnbd/null_aware_operator_A17_t07.dart
index 4d17efd..8573169 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A17_t07.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A17_t07.dart
@@ -18,6 +18,7 @@
  * @issue 39141
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 class A {
   int counter = 0;
diff --git a/LanguageFeatures/nnbd/null_aware_operator_A17_t08.dart b/LanguageFeatures/nnbd/null_aware_operator_A17_t08.dart
index 8eeecba..6719aa1 100644
--- a/LanguageFeatures/nnbd/null_aware_operator_A17_t08.dart
+++ b/LanguageFeatures/nnbd/null_aware_operator_A17_t08.dart
@@ -18,6 +18,7 @@
  * @issue 39141
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 class A {
   int counter = 0;
diff --git a/LanguageFeatures/nnbd/null_check_operator_A01_t01.dart b/LanguageFeatures/nnbd/null_check_operator_A01_t01.dart
index de2f4b5..ba27325 100644
--- a/LanguageFeatures/nnbd/null_check_operator_A01_t01.dart
+++ b/LanguageFeatures/nnbd/null_check_operator_A01_t01.dart
@@ -14,6 +14,7 @@
  * @issue 39724
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class A {
diff --git a/LanguageFeatures/nnbd/null_check_operator_A01_t02.dart b/LanguageFeatures/nnbd/null_check_operator_A01_t02.dart
index dbdb91c..d4b0f15 100644
--- a/LanguageFeatures/nnbd/null_check_operator_A01_t02.dart
+++ b/LanguageFeatures/nnbd/null_check_operator_A01_t02.dart
@@ -13,6 +13,7 @@
  * @issue 39723
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 
 class A {
   String s = "Show must go on";
diff --git a/LanguageFeatures/nnbd/null_check_operator_A02_t01.dart b/LanguageFeatures/nnbd/null_check_operator_A02_t01.dart
index 4620f75..f68189c 100644
--- a/LanguageFeatures/nnbd/null_check_operator_A02_t01.dart
+++ b/LanguageFeatures/nnbd/null_check_operator_A02_t01.dart
@@ -15,6 +15,7 @@
  * @issue 39758
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 Object? foo(int i) => null;
diff --git a/LanguageFeatures/nnbd/null_check_operator_A02_t02.dart b/LanguageFeatures/nnbd/null_check_operator_A02_t02.dart
index 9f22f12..1883427 100644
--- a/LanguageFeatures/nnbd/null_check_operator_A02_t02.dart
+++ b/LanguageFeatures/nnbd/null_check_operator_A02_t02.dart
@@ -14,6 +14,7 @@
  * @issue 39758
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 
 Object? foo(int i) => "Lily was here";
 Object? bar<T>(T t) => 42;
diff --git a/LanguageFeatures/nnbd/null_check_operator_A02_t03.dart b/LanguageFeatures/nnbd/null_check_operator_A02_t03.dart
index 0bf07f6..033d1b3 100644
--- a/LanguageFeatures/nnbd/null_check_operator_A02_t03.dart
+++ b/LanguageFeatures/nnbd/null_check_operator_A02_t03.dart
@@ -15,6 +15,7 @@
  * @issue 39758
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 
 Object? foo(int i) => "Lily was here";
 
diff --git a/LanguageFeatures/nnbd/null_check_operator_A03_t01.dart b/LanguageFeatures/nnbd/null_check_operator_A03_t01.dart
index 5ba11ee..9a2d89d 100644
--- a/LanguageFeatures/nnbd/null_check_operator_A03_t01.dart
+++ b/LanguageFeatures/nnbd/null_check_operator_A03_t01.dart
@@ -14,6 +14,7 @@
  * @issue 39598
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 
 class A {
   String s = "Show must go on";
diff --git a/LanguageFeatures/nnbd/null_check_operator_A03_t02.dart b/LanguageFeatures/nnbd/null_check_operator_A03_t02.dart
index a8844c0..24769e6 100644
--- a/LanguageFeatures/nnbd/null_check_operator_A03_t02.dart
+++ b/LanguageFeatures/nnbd/null_check_operator_A03_t02.dart
@@ -15,6 +15,8 @@
  * @issue 39598
  */
 // SharedOptions=--enable-experiment=non-nullable,extension-methods
+// Requirements=nnbd-strong
+
 import "../../Utils/expect.dart";
 class C {}
 
diff --git a/LanguageFeatures/nnbd/null_check_operator_A03_t03.dart b/LanguageFeatures/nnbd/null_check_operator_A03_t03.dart
index b977877..42eb8b6 100644
--- a/LanguageFeatures/nnbd/null_check_operator_A03_t03.dart
+++ b/LanguageFeatures/nnbd/null_check_operator_A03_t03.dart
@@ -15,6 +15,7 @@
  * @issue 39598
  */
 // SharedOptions=--enable-experiment=non-nullable,extension-methods
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/null_check_operator_A04_t01.dart b/LanguageFeatures/nnbd/null_check_operator_A04_t01.dart
index 7a2e559..6f74fee 100644
--- a/LanguageFeatures/nnbd/null_check_operator_A04_t01.dart
+++ b/LanguageFeatures/nnbd/null_check_operator_A04_t01.dart
@@ -14,6 +14,7 @@
  * @issue 39598
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 
 class A {
   String s = "Show must go on";
diff --git a/LanguageFeatures/nnbd/null_check_operator_A05_t01.dart b/LanguageFeatures/nnbd/null_check_operator_A05_t01.dart
index 37c57d8..0a9d64e 100644
--- a/LanguageFeatures/nnbd/null_check_operator_A05_t01.dart
+++ b/LanguageFeatures/nnbd/null_check_operator_A05_t01.dart
@@ -13,6 +13,7 @@
  * @issue 39723
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 
 main() {
   42!;            //# 01: static type warning
diff --git a/LanguageFeatures/nnbd/null_check_operator_A05_t02.dart b/LanguageFeatures/nnbd/null_check_operator_A05_t02.dart
index 82aded4..23caedd 100644
--- a/LanguageFeatures/nnbd/null_check_operator_A05_t02.dart
+++ b/LanguageFeatures/nnbd/null_check_operator_A05_t02.dart
@@ -14,6 +14,7 @@
  * @issue 39723
  */
 // SharedOptions=--enable-experiment=non-nullable,extension-methods
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 extension on int {
diff --git a/LanguageFeatures/nnbd/null_check_operator_A05_t03.dart b/LanguageFeatures/nnbd/null_check_operator_A05_t03.dart
index 873c743..1af1d09 100644
--- a/LanguageFeatures/nnbd/null_check_operator_A05_t03.dart
+++ b/LanguageFeatures/nnbd/null_check_operator_A05_t03.dart
@@ -13,6 +13,7 @@
  * @issue 39723
  */
 // SharedOptions=--enable-experiment=non-nullable,extension-methods
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 extension on int {
diff --git a/LanguageFeatures/nnbd/null_check_operator_A06_t01.dart b/LanguageFeatures/nnbd/null_check_operator_A06_t01.dart
index 4448061..7a19b2b 100644
--- a/LanguageFeatures/nnbd/null_check_operator_A06_t01.dart
+++ b/LanguageFeatures/nnbd/null_check_operator_A06_t01.dart
@@ -14,6 +14,7 @@
  * @issue 39724
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class A {
diff --git a/LanguageFeatures/nnbd/null_check_operator_A06_t02.dart b/LanguageFeatures/nnbd/null_check_operator_A06_t02.dart
index b270e87..5a9c849 100644
--- a/LanguageFeatures/nnbd/null_check_operator_A06_t02.dart
+++ b/LanguageFeatures/nnbd/null_check_operator_A06_t02.dart
@@ -16,6 +16,7 @@
  * @issue 39758
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class A<T> {
diff --git a/LanguageFeatures/nnbd/null_check_operator_A07_t01.dart b/LanguageFeatures/nnbd/null_check_operator_A07_t01.dart
index 79067cc..081e771 100644
--- a/LanguageFeatures/nnbd/null_check_operator_A07_t01.dart
+++ b/LanguageFeatures/nnbd/null_check_operator_A07_t01.dart
@@ -13,6 +13,7 @@
  * @issue 39723
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 
 main() {
   true!;                //# 01: static type warning
diff --git a/LanguageFeatures/nnbd/null_check_operator_A07_t02.dart b/LanguageFeatures/nnbd/null_check_operator_A07_t02.dart
index 49570c6..3ec60ec 100644
--- a/LanguageFeatures/nnbd/null_check_operator_A07_t02.dart
+++ b/LanguageFeatures/nnbd/null_check_operator_A07_t02.dart
@@ -14,6 +14,7 @@
  * @issue 39723
  */
 // SharedOptions=--enable-experiment=non-nullable,extension-methods
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 extension on bool {
diff --git a/LanguageFeatures/nnbd/null_check_operator_A07_t03.dart b/LanguageFeatures/nnbd/null_check_operator_A07_t03.dart
index 5df6786..9c0af43 100644
--- a/LanguageFeatures/nnbd/null_check_operator_A07_t03.dart
+++ b/LanguageFeatures/nnbd/null_check_operator_A07_t03.dart
@@ -13,6 +13,7 @@
  * @issue 39723
  */
 // SharedOptions=--enable-experiment=non-nullable,extension-methods
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 extension on bool {
diff --git a/LanguageFeatures/nnbd/null_promotion_A01_t01.dart b/LanguageFeatures/nnbd/null_promotion_A01_t01.dart
index d611bc2..0fe73f4 100644
--- a/LanguageFeatures/nnbd/null_promotion_A01_t01.dart
+++ b/LanguageFeatures/nnbd/null_promotion_A01_t01.dart
@@ -13,6 +13,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 
 class A {
   foo() {}
diff --git a/LanguageFeatures/nnbd/null_promotion_A01_t02.dart b/LanguageFeatures/nnbd/null_promotion_A01_t02.dart
index 1136b7d..fe09dca 100644
--- a/LanguageFeatures/nnbd/null_promotion_A01_t02.dart
+++ b/LanguageFeatures/nnbd/null_promotion_A01_t02.dart
@@ -13,6 +13,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 
 class A {
   foo() {}
diff --git a/LanguageFeatures/nnbd/null_promotion_A01_t03.dart b/LanguageFeatures/nnbd/null_promotion_A01_t03.dart
index cda52f2..c5b9e87 100644
--- a/LanguageFeatures/nnbd/null_promotion_A01_t03.dart
+++ b/LanguageFeatures/nnbd/null_promotion_A01_t03.dart
@@ -13,6 +13,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
+// Requirements=nnbd-strong
 
 class A {
   foo() {}
diff --git a/LanguageFeatures/nnbd/null_promotion_A01_t04.dart b/LanguageFeatures/nnbd/null_promotion_A01_t04.dart
index 2739b61..8631a79 100644
--- a/LanguageFeatures/nnbd/null_promotion_A01_t04.dart
+++ b/LanguageFeatures/nnbd/null_promotion_A01_t04.dart
@@ -13,6 +13,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "legacy_lib.dart";
 
 dynamic init() => null;
diff --git a/LanguageFeatures/nnbd/null_promotion_A01_t05.dart b/LanguageFeatures/nnbd/null_promotion_A01_t05.dart
index 705c08d..1bfd532 100644
--- a/LanguageFeatures/nnbd/null_promotion_A01_t05.dart
+++ b/LanguageFeatures/nnbd/null_promotion_A01_t05.dart
@@ -13,6 +13,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
+// Requirements=nnbd-strong
 import "legacy_lib.dart";
 import "legacy_library_aliases_lib.dart" as legacy;
 
diff --git a/LanguageFeatures/nnbd/null_promotion_A01_t06.dart b/LanguageFeatures/nnbd/null_promotion_A01_t06.dart
index e251752..29dd486 100644
--- a/LanguageFeatures/nnbd/null_promotion_A01_t06.dart
+++ b/LanguageFeatures/nnbd/null_promotion_A01_t06.dart
@@ -13,6 +13,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 
 class A {
   foo() {}
diff --git a/LanguageFeatures/nnbd/null_promotion_A01_t07.dart b/LanguageFeatures/nnbd/null_promotion_A01_t07.dart
index 5ab7920..8dfffec 100644
--- a/LanguageFeatures/nnbd/null_promotion_A01_t07.dart
+++ b/LanguageFeatures/nnbd/null_promotion_A01_t07.dart
@@ -13,6 +13,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 
 class A {
   foo() {}
diff --git a/LanguageFeatures/nnbd/null_promotion_A01_t08.dart b/LanguageFeatures/nnbd/null_promotion_A01_t08.dart
index b3ba981..3016b33 100644
--- a/LanguageFeatures/nnbd/null_promotion_A01_t08.dart
+++ b/LanguageFeatures/nnbd/null_promotion_A01_t08.dart
@@ -13,6 +13,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
+// Requirements=nnbd-strong
 
 class A {
   foo() {}
diff --git a/LanguageFeatures/nnbd/null_promotion_A01_t09.dart b/LanguageFeatures/nnbd/null_promotion_A01_t09.dart
index 78cc075..07a217d 100644
--- a/LanguageFeatures/nnbd/null_promotion_A01_t09.dart
+++ b/LanguageFeatures/nnbd/null_promotion_A01_t09.dart
@@ -13,6 +13,8 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
+
 import "legacy_lib.dart";
 
 dynamic init(x) => x;
diff --git a/LanguageFeatures/nnbd/null_promotion_A01_t10.dart b/LanguageFeatures/nnbd/null_promotion_A01_t10.dart
index 5870efb..4dd5c40 100644
--- a/LanguageFeatures/nnbd/null_promotion_A01_t10.dart
+++ b/LanguageFeatures/nnbd/null_promotion_A01_t10.dart
@@ -13,6 +13,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
+// Requirements=nnbd-strong
 import "legacy_lib.dart";
 import "legacy_library_aliases_lib.dart" as legacy;
 
diff --git a/LanguageFeatures/nnbd/null_promotion_A02_t01.dart b/LanguageFeatures/nnbd/null_promotion_A02_t01.dart
index 100ec03..a0507d3 100644
--- a/LanguageFeatures/nnbd/null_promotion_A02_t01.dart
+++ b/LanguageFeatures/nnbd/null_promotion_A02_t01.dart
@@ -13,6 +13,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 
 class A {
   foo() {}
diff --git a/LanguageFeatures/nnbd/null_promotion_A02_t02.dart b/LanguageFeatures/nnbd/null_promotion_A02_t02.dart
index 783303b..2ca39b9 100644
--- a/LanguageFeatures/nnbd/null_promotion_A02_t02.dart
+++ b/LanguageFeatures/nnbd/null_promotion_A02_t02.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 
 class A {
   foo() {}
diff --git a/LanguageFeatures/nnbd/null_promotion_A02_t03.dart b/LanguageFeatures/nnbd/null_promotion_A02_t03.dart
index efa3373..635e7ce 100644
--- a/LanguageFeatures/nnbd/null_promotion_A02_t03.dart
+++ b/LanguageFeatures/nnbd/null_promotion_A02_t03.dart
@@ -13,6 +13,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
+// Requirements=nnbd-strong
 
 class A {
   foo() {}
diff --git a/LanguageFeatures/nnbd/null_promotion_A02_t04.dart b/LanguageFeatures/nnbd/null_promotion_A02_t04.dart
index c84c8f9..16b2a22 100644
--- a/LanguageFeatures/nnbd/null_promotion_A02_t04.dart
+++ b/LanguageFeatures/nnbd/null_promotion_A02_t04.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
+// Requirements=nnbd-strong
 
 class A {
   foo() {}
diff --git a/LanguageFeatures/nnbd/null_promotion_A02_t05.dart b/LanguageFeatures/nnbd/null_promotion_A02_t05.dart
index 7126548..9a79db1 100644
--- a/LanguageFeatures/nnbd/null_promotion_A02_t05.dart
+++ b/LanguageFeatures/nnbd/null_promotion_A02_t05.dart
@@ -13,6 +13,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "legacy_lib.dart";
 
 main() {
diff --git a/LanguageFeatures/nnbd/null_promotion_A02_t06.dart b/LanguageFeatures/nnbd/null_promotion_A02_t06.dart
index 0302019..fc682ea 100644
--- a/LanguageFeatures/nnbd/null_promotion_A02_t06.dart
+++ b/LanguageFeatures/nnbd/null_promotion_A02_t06.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "legacy_lib.dart";
 import "legacy_library_aliases_lib.dart" as aliases;
 
diff --git a/LanguageFeatures/nnbd/null_promotion_A02_t07.dart b/LanguageFeatures/nnbd/null_promotion_A02_t07.dart
index 04e95c1..bda08d1 100644
--- a/LanguageFeatures/nnbd/null_promotion_A02_t07.dart
+++ b/LanguageFeatures/nnbd/null_promotion_A02_t07.dart
@@ -13,6 +13,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "legacy_lib.dart";
 
 main() {
diff --git a/LanguageFeatures/nnbd/null_promotion_A02_t08.dart b/LanguageFeatures/nnbd/null_promotion_A02_t08.dart
index c6cedf1..88af0a2 100644
--- a/LanguageFeatures/nnbd/null_promotion_A02_t08.dart
+++ b/LanguageFeatures/nnbd/null_promotion_A02_t08.dart
@@ -14,6 +14,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "legacy_lib.dart";
 import "legacy_library_aliases_lib.dart" as aliases;
 
diff --git a/LanguageFeatures/nnbd/opted_in_aliases_lib.dart b/LanguageFeatures/nnbd/opted_in_aliases_lib.dart
index 6067720..f9f47e4 100644
--- a/LanguageFeatures/nnbd/opted_in_aliases_lib.dart
+++ b/LanguageFeatures/nnbd/opted_in_aliases_lib.dart
@@ -7,6 +7,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
+// Requirements=nnbd-strong
 library opted_in_aliases_lib;
 
 class A {
diff --git a/LanguageFeatures/nnbd/opted_in_lib.dart b/LanguageFeatures/nnbd/opted_in_lib.dart
index 8a86a75..4ec23e9 100644
--- a/LanguageFeatures/nnbd/opted_in_lib.dart
+++ b/LanguageFeatures/nnbd/opted_in_lib.dart
@@ -7,6 +7,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 library opted_in_lib;
 
 class A {
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t01.dart b/LanguageFeatures/nnbd/override_checking_A01_t01.dart
index 99626bc..c39a079 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t01.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t01.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t02.dart b/LanguageFeatures/nnbd/override_checking_A01_t02.dart
index b4ad872..c90a8aa 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t02.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t02.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t03.dart b/LanguageFeatures/nnbd/override_checking_A01_t03.dart
index d9ef0df..fceb399 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t03.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t03.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t04.dart b/LanguageFeatures/nnbd/override_checking_A01_t04.dart
index c7c39cb..320ad92 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t04.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t04.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t05.dart b/LanguageFeatures/nnbd/override_checking_A01_t05.dart
index dd18765..b6060c2 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t05.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t05.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t06.dart b/LanguageFeatures/nnbd/override_checking_A01_t06.dart
index 3bfb103..d8647b2 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t06.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t06.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t07.dart b/LanguageFeatures/nnbd/override_checking_A01_t07.dart
index f8c40fa..d84294c 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t07.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t07.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t08.dart b/LanguageFeatures/nnbd/override_checking_A01_t08.dart
index d8acf80..a8b84ad 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t08.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t08.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t09.dart b/LanguageFeatures/nnbd/override_checking_A01_t09.dart
index b0351d5..cb46b2e 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t09.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t09.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t10.dart b/LanguageFeatures/nnbd/override_checking_A01_t10.dart
index f17d9b3..063c591 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t10.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t10.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t11.dart b/LanguageFeatures/nnbd/override_checking_A01_t11.dart
index 9568de7..bf48084 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t11.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t11.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t12.dart b/LanguageFeatures/nnbd/override_checking_A01_t12.dart
index fcda98b..77d7311 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t12.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t12.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t13.dart b/LanguageFeatures/nnbd/override_checking_A01_t13.dart
index db1817e..4f92b24 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t13.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t13.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t14.dart b/LanguageFeatures/nnbd/override_checking_A01_t14.dart
index f153b9f..8c4777c 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t14.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t14.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t15.dart b/LanguageFeatures/nnbd/override_checking_A01_t15.dart
index 3d33d37..403aabb 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t15.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t15.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t16.dart b/LanguageFeatures/nnbd/override_checking_A01_t16.dart
index 7c63cec..46ba070 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t16.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t16.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t17.dart b/LanguageFeatures/nnbd/override_checking_A01_t17.dart
index ee432e0..5434bb2 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t17.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t17.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "override_checking_opted_in_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t18.dart b/LanguageFeatures/nnbd/override_checking_A01_t18.dart
index eb334ed..ddaac49 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t18.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t18.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t19.dart b/LanguageFeatures/nnbd/override_checking_A01_t19.dart
index d18a8b6..f36b3cb 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t19.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t19.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t20.dart b/LanguageFeatures/nnbd/override_checking_A01_t20.dart
index 10af577..eaeff13 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t20.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t20.dart
@@ -18,7 +18,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t21.dart b/LanguageFeatures/nnbd/override_checking_A01_t21.dart
index 418fb81..86d45e8 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t21.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t21.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t22.dart b/LanguageFeatures/nnbd/override_checking_A01_t22.dart
index 54276a2..5c811cb 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t22.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t22.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t23.dart b/LanguageFeatures/nnbd/override_checking_A01_t23.dart
index 1b41262..34a71e6 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t23.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t23.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t24.dart b/LanguageFeatures/nnbd/override_checking_A01_t24.dart
index ef14ac7..0678776 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t24.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t24.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t25.dart b/LanguageFeatures/nnbd/override_checking_A01_t25.dart
index c118bef..ea6cc83 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t25.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t25.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t26.dart b/LanguageFeatures/nnbd/override_checking_A01_t26.dart
index f327dd9..9c476f7 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t26.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t26.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t27.dart b/LanguageFeatures/nnbd/override_checking_A01_t27.dart
index 6ef1533..43c0185 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t27.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t27.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t28.dart b/LanguageFeatures/nnbd/override_checking_A01_t28.dart
index 10ef6b5..0566fb7 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t28.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t28.dart
@@ -22,7 +22,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t29.dart b/LanguageFeatures/nnbd/override_checking_A01_t29.dart
index df47287..b323d46 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t29.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t29.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t30.dart b/LanguageFeatures/nnbd/override_checking_A01_t30.dart
index 11dfdd5..0ee3bbc 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t30.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t30.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t31.dart b/LanguageFeatures/nnbd/override_checking_A01_t31.dart
index c106ac4..e7ce0d1 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t31.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t31.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t32.dart b/LanguageFeatures/nnbd/override_checking_A01_t32.dart
index a845111..b522328 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t32.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t32.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t33.dart b/LanguageFeatures/nnbd/override_checking_A01_t33.dart
index 455e4cb..e1353c1 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t33.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t33.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t34.dart b/LanguageFeatures/nnbd/override_checking_A01_t34.dart
index 05dc476..d9ee641 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t34.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t34.dart
@@ -18,7 +18,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "override_checking_opted_in_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t35.dart b/LanguageFeatures/nnbd/override_checking_A01_t35.dart
index a9eae67..09c80cc 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t35.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t35.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t36.dart b/LanguageFeatures/nnbd/override_checking_A01_t36.dart
index e472cbc..114afb6 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t36.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t36.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t37.dart b/LanguageFeatures/nnbd/override_checking_A01_t37.dart
index beb9e2b..1175b4b 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t37.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t37.dart
@@ -18,7 +18,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t38.dart b/LanguageFeatures/nnbd/override_checking_A01_t38.dart
index b16d74f..bf13cff 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t38.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t38.dart
@@ -18,7 +18,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t39.dart b/LanguageFeatures/nnbd/override_checking_A01_t39.dart
index 55dfdf2..c548f0c 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t39.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t39.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t40.dart b/LanguageFeatures/nnbd/override_checking_A01_t40.dart
index edbd25c..68f9377 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t40.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t40.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t41.dart b/LanguageFeatures/nnbd/override_checking_A01_t41.dart
index 7a9bc9a..aefbe94 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t41.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t41.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t42.dart b/LanguageFeatures/nnbd/override_checking_A01_t42.dart
index 9ecf197..b7ef3df 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t42.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t42.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t43.dart b/LanguageFeatures/nnbd/override_checking_A01_t43.dart
index 6eac444..4512235 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t43.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t43.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t44.dart b/LanguageFeatures/nnbd/override_checking_A01_t44.dart
index f2f5fd4..d47b83e 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t44.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t44.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t45.dart b/LanguageFeatures/nnbd/override_checking_A01_t45.dart
index 3042b71..f7d75c0 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t45.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t45.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t46.dart b/LanguageFeatures/nnbd/override_checking_A01_t46.dart
index 25c36b4..c3fae80 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t46.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t46.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t47.dart b/LanguageFeatures/nnbd/override_checking_A01_t47.dart
index 0c3cf08..36ad90a 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t47.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t47.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t48.dart b/LanguageFeatures/nnbd/override_checking_A01_t48.dart
index 0724c90..5cd4cc2 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t48.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t48.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t49.dart b/LanguageFeatures/nnbd/override_checking_A01_t49.dart
index 847a6b5..aa0e6f4 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t49.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t49.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t50.dart b/LanguageFeatures/nnbd/override_checking_A01_t50.dart
index cc8d2e9..7af096f 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t50.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t50.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t51.dart b/LanguageFeatures/nnbd/override_checking_A01_t51.dart
index 2eb907f..06aa458 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t51.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t51.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "override_checking_opted_in_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t52.dart b/LanguageFeatures/nnbd/override_checking_A01_t52.dart
index 90c16ab..10c9a28 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t52.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t52.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t53.dart b/LanguageFeatures/nnbd/override_checking_A01_t53.dart
index dbec895..9491184 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t53.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t53.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t54.dart b/LanguageFeatures/nnbd/override_checking_A01_t54.dart
index 326993a..8dde91c 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t54.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t54.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t55.dart b/LanguageFeatures/nnbd/override_checking_A01_t55.dart
index fbcd375..08410c3 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t55.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t55.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t56.dart b/LanguageFeatures/nnbd/override_checking_A01_t56.dart
index 44e560d..102fd6e 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t56.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t56.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t57.dart b/LanguageFeatures/nnbd/override_checking_A01_t57.dart
index 9d9945c..9bccd87 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t57.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t57.dart
@@ -18,7 +18,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t58.dart b/LanguageFeatures/nnbd/override_checking_A01_t58.dart
index 93e5d83..dc59ebf 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t58.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t58.dart
@@ -18,7 +18,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t59.dart b/LanguageFeatures/nnbd/override_checking_A01_t59.dart
index 42809ca..d79fc8f 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t59.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t59.dart
@@ -18,7 +18,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t60.dart b/LanguageFeatures/nnbd/override_checking_A01_t60.dart
index cf01acc..dac224d 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t60.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t60.dart
@@ -18,7 +18,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t61.dart b/LanguageFeatures/nnbd/override_checking_A01_t61.dart
index a81780d..6bd9dd7 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t61.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t61.dart
@@ -18,7 +18,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t62.dart b/LanguageFeatures/nnbd/override_checking_A01_t62.dart
index 0a59298..958b895 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t62.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t62.dart
@@ -18,7 +18,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t63.dart b/LanguageFeatures/nnbd/override_checking_A01_t63.dart
index bbf8594..4cb4081 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t63.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t63.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t64.dart b/LanguageFeatures/nnbd/override_checking_A01_t64.dart
index 91571b7..de3ff1d 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t64.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t64.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t65.dart b/LanguageFeatures/nnbd/override_checking_A01_t65.dart
index 33aeb76..947d522 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t65.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t65.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t66.dart b/LanguageFeatures/nnbd/override_checking_A01_t66.dart
index 79ae3be..42d7c1a 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t66.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t66.dart
@@ -18,7 +18,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t67.dart b/LanguageFeatures/nnbd/override_checking_A01_t67.dart
index ce5aa87..831895f 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t67.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t67.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "../../Utils/expect.dart";
 import "override_checking_opted_in_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A01_t68.dart b/LanguageFeatures/nnbd/override_checking_A01_t68.dart
index 0417cb3..12e89b1 100644
--- a/LanguageFeatures/nnbd/override_checking_A01_t68.dart
+++ b/LanguageFeatures/nnbd/override_checking_A01_t68.dart
@@ -18,7 +18,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 import "override_checking_opted_in_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t01.dart b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t01.dart
index 1cd28e6..bc078bf 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t01.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t01.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t02.dart b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t02.dart
index efdef7d..68dee5f 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t02.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t02.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t03.dart b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t03.dart
index c54cf65..d5a47fe 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t03.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t03.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "override_checking_legacy_lib.dart";
 import "../../Utils/expect.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t04.dart b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t04.dart
index cb63015..290493c 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t04.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t04.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t05.dart b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t05.dart
index fc8c655..030fb1a 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t05.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t05.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t06.dart b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t06.dart
index 0defe30..3a5ca45 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t06.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t06.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t07.dart b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t07.dart
index 9511c71..ad283ef 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t07.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t07.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t08.dart b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t08.dart
index 81c278c..474113d 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t08.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t08.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "override_checking_legacy_lib.dart";
 import "../../Utils/expect.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t09.dart b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t09.dart
index cd30a9a..a7b0937 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t09.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t09.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t10.dart b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t10.dart
index dfe129d..d30e157 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t10.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t10.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t11.dart b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t11.dart
index a1769e5..d5c5d69 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t11.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t11.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t12.dart b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t12.dart
index 722cd99..245d902 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t12.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t12.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t13.dart b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t13.dart
index 3ae1496..baa0860 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t13.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t13.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "override_checking_legacy_lib.dart";
 import "../../Utils/expect.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t14.dart b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t14.dart
index fb5ab23..fd15897 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t14.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t14.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t15.dart b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t15.dart
index eaa3d61..41348ac 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t15.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t15.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t16.dart b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t16.dart
index de2c8cb..e28b1c1 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t16.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t16.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t17.dart b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t17.dart
index da56fb7..9d1dd36 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t17.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t17.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t18.dart b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t18.dart
index a618aea..447a001 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t18.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t18.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t19.dart b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t19.dart
index 8512a06..7c835de 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t19.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t19.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t20.dart b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t20.dart
index 2b234f4..69eb226 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t20.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t20.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t21.dart b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t21.dart
index 3dd0137..0be9228 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t21.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t21.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "override_checking_legacy_lib.dart";
 
 class A extends LEGACY_ARGS {
diff --git a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t22.dart b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t22.dart
index 11c9ad6..b4225a6 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t22.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t22.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "override_checking_legacy_lib.dart";
 
 class A implements LEGACY_ARGS {
diff --git a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t23.dart b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t23.dart
index 9dc0f3b..c7ae6e6 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t23.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t23.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "override_checking_legacy_lib.dart";
 
 class A with LEGACY_ARGS {
diff --git a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t24.dart b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t24.dart
index f9a5c4b..bff505d 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_ARGS_t24.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_ARGS_t24.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "override_checking_legacy_lib.dart";
 
 class B {
diff --git a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t01.dart b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t01.dart
index aeea4e6..b5fab07 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t01.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t01.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t02.dart b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t02.dart
index 8e50e34..da181cb 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t02.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t02.dart
@@ -18,7 +18,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t03.dart b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t03.dart
index 31c4e39..41ae796 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t03.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t03.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t04.dart b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t04.dart
index 8d4dcc3..6e0feb1 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t04.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t04.dart
@@ -18,7 +18,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_futureor_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t05.dart b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t05.dart
index 188daf8..2039620 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t05.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t05.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t06.dart b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t06.dart
index 887c644..c566126 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t06.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t06.dart
@@ -18,7 +18,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_futureor_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t07.dart b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t07.dart
index a8999dc..13c0914 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t07.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t07.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t08.dart b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t08.dart
index f8d33e8..5f6ee33 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t08.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t08.dart
@@ -18,7 +18,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_futureor_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t09.dart b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t09.dart
index 4a6a6b9..4d83030 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t09.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t09.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t10.dart b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t10.dart
index 56c6f78..265e420 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t10.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t10.dart
@@ -18,7 +18,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_futureor_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t11.dart b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t11.dart
index 7e59a4b..54584c9 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t11.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t11.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t12.dart b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t12.dart
index 0355f0f..e2bc0e6 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t12.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t12.dart
@@ -18,7 +18,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_futureor_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t13.dart b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t13.dart
index ac2df7d..d440288 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t13.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t13.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t14.dart b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t14.dart
index 5ba88fb..d3cedc0 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t14.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t14.dart
@@ -18,7 +18,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_futureor_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t15.dart b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t15.dart
index d8bf8a1..7448d1d 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t15.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t15.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t16.dart b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t16.dart
index 97d1187..61e1c5c 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t16.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t16.dart
@@ -19,7 +19,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_futureor_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t17.dart b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t17.dart
index 40935e0..d99c7ff 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t17.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t17.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t18.dart b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t18.dart
index 811cda2..dbf453b 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t18.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t18.dart
@@ -18,7 +18,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_futureor_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t19.dart b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t19.dart
index a3d8618..6fb7916 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t19.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t19.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t20.dart b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t20.dart
index cc8d964..054cbd5 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t20.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t20.dart
@@ -18,7 +18,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_futureor_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t21.dart b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t21.dart
index 9a07cc2..8c63c26 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t21.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t21.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t22.dart b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t22.dart
index 8f6ef28..297799c 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t22.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t22.dart
@@ -19,7 +19,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_futureor_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t23.dart b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t23.dart
index 627cbda..6c29082 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t23.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t23.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t24.dart b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t24.dart
index ceb662a..c4586c8 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t24.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_CLASSPARAM_t24.dart
@@ -18,7 +18,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_futureor_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_FIELD_t01.dart b/LanguageFeatures/nnbd/override_checking_A02_FIELD_t01.dart
index 2e5b6b2..f30a70e 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_FIELD_t01.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_FIELD_t01.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
 */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_FIELD_t02.dart b/LanguageFeatures/nnbd/override_checking_A02_FIELD_t02.dart
index c2eab4c..cfebb63 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_FIELD_t02.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_FIELD_t02.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
 */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "override_checking_legacy_lib.dart";
 import "../../Utils/expect.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_FIELD_t03.dart b/LanguageFeatures/nnbd/override_checking_A02_FIELD_t03.dart
index 1f6d187..a1ea927 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_FIELD_t03.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_FIELD_t03.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
 */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_FIELD_t04.dart b/LanguageFeatures/nnbd/override_checking_A02_FIELD_t04.dart
index 8eed77c..0a62829 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_FIELD_t04.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_FIELD_t04.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
 */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "override_checking_legacy_lib.dart";
 import "../../Utils/expect.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_FIELD_t05.dart b/LanguageFeatures/nnbd/override_checking_A02_FIELD_t05.dart
index fd2c49f..8f22cfc 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_FIELD_t05.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_FIELD_t05.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
 */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_FIELD_t06.dart b/LanguageFeatures/nnbd/override_checking_A02_FIELD_t06.dart
index fe0b619..acb89d4 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_FIELD_t06.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_FIELD_t06.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
 */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "override_checking_legacy_lib.dart";
 import "../../Utils/expect.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_FIELD_t07.dart b/LanguageFeatures/nnbd/override_checking_A02_FIELD_t07.dart
index 12db758..9e04816 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_FIELD_t07.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_FIELD_t07.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
 */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_FIELD_t08.dart b/LanguageFeatures/nnbd/override_checking_A02_FIELD_t08.dart
index feb82b4..331b8ad 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_FIELD_t08.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_FIELD_t08.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
 */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "override_checking_legacy_lib.dart";
 import "../../Utils/expect.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_FIELD_t09.dart b/LanguageFeatures/nnbd/override_checking_A02_FIELD_t09.dart
index bc057f2..f449a66 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_FIELD_t09.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_FIELD_t09.dart
@@ -18,7 +18,7 @@
  * @author iarkh@unipro.ru
 */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "override_checking_legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A02_FIELD_t10.dart b/LanguageFeatures/nnbd/override_checking_A02_FIELD_t10.dart
index 30c52a4..df6cf85 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_FIELD_t10.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_FIELD_t10.dart
@@ -18,7 +18,7 @@
  * @author iarkh@unipro.ru
 */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "override_checking_legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A02_FIELD_t11.dart b/LanguageFeatures/nnbd/override_checking_A02_FIELD_t11.dart
index 4e4df05..2a31e9b 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_FIELD_t11.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_FIELD_t11.dart
@@ -18,7 +18,7 @@
  * @author iarkh@unipro.ru
 */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "override_checking_legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A02_FIELD_t12.dart b/LanguageFeatures/nnbd/override_checking_A02_FIELD_t12.dart
index 6e87e80..75a936c 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_FIELD_t12.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_FIELD_t12.dart
@@ -18,7 +18,7 @@
  * @author iarkh@unipro.ru
 */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "override_checking_legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A02_GETTER_t01.dart b/LanguageFeatures/nnbd/override_checking_A02_GETTER_t01.dart
index dc2f818..222dfae 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_GETTER_t01.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_GETTER_t01.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_GETTER_t02.dart b/LanguageFeatures/nnbd/override_checking_A02_GETTER_t02.dart
index 363448b..b69b108 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_GETTER_t02.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_GETTER_t02.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_GETTER_t03.dart b/LanguageFeatures/nnbd/override_checking_A02_GETTER_t03.dart
index 08e0779..d302d47 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_GETTER_t03.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_GETTER_t03.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_GETTER_t04.dart b/LanguageFeatures/nnbd/override_checking_A02_GETTER_t04.dart
index 9878435..230b081 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_GETTER_t04.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_GETTER_t04.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_GETTER_t05.dart b/LanguageFeatures/nnbd/override_checking_A02_GETTER_t05.dart
index 132bc2b..47d2eb2 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_GETTER_t05.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_GETTER_t05.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_GETTER_t06.dart b/LanguageFeatures/nnbd/override_checking_A02_GETTER_t06.dart
index c9de37c..43eed51 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_GETTER_t06.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_GETTER_t06.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_GETTER_t07.dart b/LanguageFeatures/nnbd/override_checking_A02_GETTER_t07.dart
index 11529ba..1556149 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_GETTER_t07.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_GETTER_t07.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_GETTER_t08.dart b/LanguageFeatures/nnbd/override_checking_A02_GETTER_t08.dart
index 452bfff..dab3525 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_GETTER_t08.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_GETTER_t08.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_GETTER_t09.dart b/LanguageFeatures/nnbd/override_checking_A02_GETTER_t09.dart
index dbe2739..fc1cba1 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_GETTER_t09.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_GETTER_t09.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_GETTER_t10.dart b/LanguageFeatures/nnbd/override_checking_A02_GETTER_t10.dart
index f021b78..06d7979 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_GETTER_t10.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_GETTER_t10.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_GETTER_t11.dart b/LanguageFeatures/nnbd/override_checking_A02_GETTER_t11.dart
index af3e000..4be220a 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_GETTER_t11.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_GETTER_t11.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_GETTER_t12.dart b/LanguageFeatures/nnbd/override_checking_A02_GETTER_t12.dart
index 27ea069..ad8c0ca 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_GETTER_t12.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_GETTER_t12.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t01.dart b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t01.dart
index 093e86e..31486d9 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t01.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t01.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t02.dart b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t02.dart
index 370f9a1..a54fcc9 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t02.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t02.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "override_checking_legacy_lib.dart";
 
 class A extends LEGACY_REQUIRED_ARGS {
diff --git a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t03.dart b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t03.dart
index 01eb667..00cccfa 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t03.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t03.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t04.dart b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t04.dart
index 92777c3..7efe174 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t04.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t04.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "override_checking_legacy_lib.dart";
 
 class A1 implements LEGACY_REQUIRED_ARGS {
diff --git a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t05.dart b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t05.dart
index 7fa470c..97fcf37 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t05.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t05.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t06.dart b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t06.dart
index 080856b..794e48f 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t06.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t06.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "override_checking_legacy_lib.dart";
 
 class A1 with LEGACY_REQUIRED_ARGS {
diff --git a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t07.dart b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t07.dart
index bf9e4b9..e3188a3 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t07.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t07.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t08.dart b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t08.dart
index 4aacb18..3f6147e 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t08.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t08.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "override_checking_legacy_lib.dart";
 
 abstract class B {
diff --git a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t09.dart b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t09.dart
index cc1971c..3942c67 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t09.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t09.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "override_checking_legacy_lib.dart";
 import "../../Utils/expect.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t10.dart b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t10.dart
index 8ddeb76..97adf2e 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t10.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t10.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "override_checking_legacy_lib.dart";
 
 class A1 extends LEGACY_REQUIRED_ARGS {
diff --git a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t11.dart b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t11.dart
index f78f7c0..c5a8e43 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t11.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t11.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "override_checking_legacy_lib.dart";
 import "../../Utils/expect.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t12.dart b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t12.dart
index b03d58c..c838cde 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t12.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t12.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "override_checking_legacy_lib.dart";
 
 class A1 implements LEGACY_REQUIRED_ARGS {
diff --git a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t13.dart b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t13.dart
index 78a4879..6d7833d 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t13.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t13.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "override_checking_legacy_lib.dart";
 import "../../Utils/expect.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t14.dart b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t14.dart
index 6aa66e5..c0dda9f 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t14.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t14.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "override_checking_legacy_lib.dart";
 
 class A1 with LEGACY_REQUIRED_ARGS {
diff --git a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t15.dart b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t15.dart
index 0d33ba5..47eec9a 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t15.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t15.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "override_checking_legacy_lib.dart";
 import "../../Utils/expect.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t16.dart b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t16.dart
index 95e2eb9..2c518c3 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t16.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t16.dart
@@ -17,7 +17,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "override_checking_legacy_lib.dart";
 
 abstract class B {
diff --git a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t17.dart b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t17.dart
index 7b7b47c..3ee732d 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t17.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t17.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "override_checking_legacy_lib.dart";
 import "../../Utils/expect.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t18.dart b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t18.dart
index 34c9d10..62a988b 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t18.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t18.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "override_checking_legacy_lib.dart";
 import "../../Utils/expect.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t19.dart b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t19.dart
index db214de..52d6f5b 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t19.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t19.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "override_checking_legacy_lib.dart";
 import "../../Utils/expect.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t20.dart b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t20.dart
index a666c23..c854c7e 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t20.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_REQ_ARGS_t20.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "override_checking_legacy_lib.dart";
 import "../../Utils/expect.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A02_RETURN_t01.dart b/LanguageFeatures/nnbd/override_checking_A02_RETURN_t01.dart
index 96b0119..4df7097 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_RETURN_t01.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_RETURN_t01.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_RETURN_t02.dart b/LanguageFeatures/nnbd/override_checking_A02_RETURN_t02.dart
index 5b88630..d397b61 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_RETURN_t02.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_RETURN_t02.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_RETURN_t03.dart b/LanguageFeatures/nnbd/override_checking_A02_RETURN_t03.dart
index 558a969..3854856 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_RETURN_t03.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_RETURN_t03.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_RETURN_t04.dart b/LanguageFeatures/nnbd/override_checking_A02_RETURN_t04.dart
index b80f17a..53e1bce 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_RETURN_t04.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_RETURN_t04.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_RETURN_t05.dart b/LanguageFeatures/nnbd/override_checking_A02_RETURN_t05.dart
index 90ed933..7c5922f 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_RETURN_t05.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_RETURN_t05.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_RETURN_t06.dart b/LanguageFeatures/nnbd/override_checking_A02_RETURN_t06.dart
index 0129bb3..78b3a82 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_RETURN_t06.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_RETURN_t06.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_RETURN_t07.dart b/LanguageFeatures/nnbd/override_checking_A02_RETURN_t07.dart
index 81e3e75..56189c7 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_RETURN_t07.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_RETURN_t07.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_RETURN_t08.dart b/LanguageFeatures/nnbd/override_checking_A02_RETURN_t08.dart
index 00d4a16..ca1a0be 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_RETURN_t08.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_RETURN_t08.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_RETURN_t09.dart b/LanguageFeatures/nnbd/override_checking_A02_RETURN_t09.dart
index 6eb52d1..49008e9 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_RETURN_t09.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_RETURN_t09.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_RETURN_t10.dart b/LanguageFeatures/nnbd/override_checking_A02_RETURN_t10.dart
index 988d8b5..c81dd2a 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_RETURN_t10.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_RETURN_t10.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_RETURN_t11.dart b/LanguageFeatures/nnbd/override_checking_A02_RETURN_t11.dart
index c2eb845..5f6d3d7 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_RETURN_t11.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_RETURN_t11.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_RETURN_t12.dart b/LanguageFeatures/nnbd/override_checking_A02_RETURN_t12.dart
index cbd3862..805387b 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_RETURN_t12.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_RETURN_t12.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_RETURN_t13.dart b/LanguageFeatures/nnbd/override_checking_A02_RETURN_t13.dart
index 27ba7bb..7880c60 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_RETURN_t13.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_RETURN_t13.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "override_checking_legacy_lib.dart";
 import "../../Utils/expect.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A02_RETURN_t14.dart b/LanguageFeatures/nnbd/override_checking_A02_RETURN_t14.dart
index 7ac57f4..2f3a329 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_RETURN_t14.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_RETURN_t14.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "override_checking_legacy_lib.dart";
 import "../../Utils/expect.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A02_RETURN_t15.dart b/LanguageFeatures/nnbd/override_checking_A02_RETURN_t15.dart
index e0b92fa..96d854a 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_RETURN_t15.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_RETURN_t15.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "override_checking_legacy_lib.dart";
 import "../../Utils/expect.dart";
 
diff --git a/LanguageFeatures/nnbd/override_checking_A02_RETURN_t16.dart b/LanguageFeatures/nnbd/override_checking_A02_RETURN_t16.dart
index 35b7636..cd026d4 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_RETURN_t16.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_RETURN_t16.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "override_checking_legacy_lib.dart";
 import "../../Utils/expect.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_SETTER_t01.dart b/LanguageFeatures/nnbd/override_checking_A02_SETTER_t01.dart
index b68fabd..4fc6bed 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_SETTER_t01.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_SETTER_t01.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_SETTER_t02.dart b/LanguageFeatures/nnbd/override_checking_A02_SETTER_t02.dart
index 27ae828..da0f5fa 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_SETTER_t02.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_SETTER_t02.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_SETTER_t03.dart b/LanguageFeatures/nnbd/override_checking_A02_SETTER_t03.dart
index b6eda98..b5d93b3 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_SETTER_t03.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_SETTER_t03.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "override_checking_legacy_lib.dart";
 import "../../Utils/expect.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_SETTER_t04.dart b/LanguageFeatures/nnbd/override_checking_A02_SETTER_t04.dart
index a8d5563..91f03f1 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_SETTER_t04.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_SETTER_t04.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_SETTER_t05.dart b/LanguageFeatures/nnbd/override_checking_A02_SETTER_t05.dart
index 0308332..94cfc69 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_SETTER_t05.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_SETTER_t05.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_SETTER_t06.dart b/LanguageFeatures/nnbd/override_checking_A02_SETTER_t06.dart
index 0fbf503..fcdb140 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_SETTER_t06.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_SETTER_t06.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "override_checking_legacy_lib.dart";
 import "../../Utils/expect.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_SETTER_t07.dart b/LanguageFeatures/nnbd/override_checking_A02_SETTER_t07.dart
index 0e3a118..f440845 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_SETTER_t07.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_SETTER_t07.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_SETTER_t08.dart b/LanguageFeatures/nnbd/override_checking_A02_SETTER_t08.dart
index a25cc1d..2bcecea 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_SETTER_t08.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_SETTER_t08.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_SETTER_t09.dart b/LanguageFeatures/nnbd/override_checking_A02_SETTER_t09.dart
index 5838373..3798d99 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_SETTER_t09.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_SETTER_t09.dart
@@ -15,7 +15,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "override_checking_legacy_lib.dart";
 import "../../Utils/expect.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_SETTER_t10.dart b/LanguageFeatures/nnbd/override_checking_A02_SETTER_t10.dart
index 79101ac..3810c5f 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_SETTER_t10.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_SETTER_t10.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_SETTER_t11.dart b/LanguageFeatures/nnbd/override_checking_A02_SETTER_t11.dart
index a464a2d..a55525e 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_SETTER_t11.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_SETTER_t11.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "../../Utils/expect.dart";
 import "override_checking_legacy_lib.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_A02_SETTER_t12.dart b/LanguageFeatures/nnbd/override_checking_A02_SETTER_t12.dart
index a7d140f..485c61f 100644
--- a/LanguageFeatures/nnbd/override_checking_A02_SETTER_t12.dart
+++ b/LanguageFeatures/nnbd/override_checking_A02_SETTER_t12.dart
@@ -16,7 +16,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "dart:async";
 import "override_checking_legacy_lib.dart";
 import "../../Utils/expect.dart";
diff --git a/LanguageFeatures/nnbd/override_checking_legacy_futureor_lib.dart b/LanguageFeatures/nnbd/override_checking_legacy_futureor_lib.dart
index d2fc093..a15f23b 100644
--- a/LanguageFeatures/nnbd/override_checking_legacy_futureor_lib.dart
+++ b/LanguageFeatures/nnbd/override_checking_legacy_futureor_lib.dart
@@ -10,7 +10,7 @@
  *
  * @author iarkh@unipro.ru
  */
-// @dart=2.4
+// @dart=2.6
 // SharedOptions=--enable-experiment=non-nullable
 
 library override_legacy_futureor_lib;
diff --git a/LanguageFeatures/nnbd/override_checking_legacy_lib.dart b/LanguageFeatures/nnbd/override_checking_legacy_lib.dart
index cdddccb..b148a1f 100644
--- a/LanguageFeatures/nnbd/override_checking_legacy_lib.dart
+++ b/LanguageFeatures/nnbd/override_checking_legacy_lib.dart
@@ -6,7 +6,7 @@
 /**
  * @author iarkh@unipro.ru
  */
-// @dart=2.4
+// @dart=2.6
 // SharedOptions=--enable-experiment=non-nullable
 
 library override_legacy_lib;
diff --git a/LanguageFeatures/nnbd/override_checking_opted_in_lib.dart b/LanguageFeatures/nnbd/override_checking_opted_in_lib.dart
index 14a2db6..8b7d193 100644
--- a/LanguageFeatures/nnbd/override_checking_opted_in_lib.dart
+++ b/LanguageFeatures/nnbd/override_checking_opted_in_lib.dart
@@ -7,6 +7,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 
 library override_opted_in_lib;
 
diff --git a/LanguageFeatures/nnbd/static_errors_A02_t04.dart b/LanguageFeatures/nnbd/static_errors_A02_t04.dart
index 358acb5..74c8afa 100644
--- a/LanguageFeatures/nnbd/static_errors_A02_t04.dart
+++ b/LanguageFeatures/nnbd/static_errors_A02_t04.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
+// Requirements=nnbd-strong
 
 class A {
   final String s = "Lily was here";
diff --git a/LanguageFeatures/nnbd/static_errors_A16_t01.dart b/LanguageFeatures/nnbd/static_errors_A16_t01.dart
index 1b75d53..f09354c 100644
--- a/LanguageFeatures/nnbd/static_errors_A16_t01.dart
+++ b/LanguageFeatures/nnbd/static_errors_A16_t01.dart
@@ -12,6 +12,7 @@
  * @issue 39658
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/static_errors_A16_t02.dart b/LanguageFeatures/nnbd/static_errors_A16_t02.dart
index 85c7a36..a40409c 100644
--- a/LanguageFeatures/nnbd/static_errors_A16_t02.dart
+++ b/LanguageFeatures/nnbd/static_errors_A16_t02.dart
@@ -11,6 +11,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class A {
diff --git a/LanguageFeatures/nnbd/static_errors_A16_t03.dart b/LanguageFeatures/nnbd/static_errors_A16_t03.dart
index e99a9d8..692dcb7 100644
--- a/LanguageFeatures/nnbd/static_errors_A16_t03.dart
+++ b/LanguageFeatures/nnbd/static_errors_A16_t03.dart
@@ -11,6 +11,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/static_errors_A17_t01.dart b/LanguageFeatures/nnbd/static_errors_A17_t01.dart
index 166b44e..412afdb 100644
--- a/LanguageFeatures/nnbd/static_errors_A17_t01.dart
+++ b/LanguageFeatures/nnbd/static_errors_A17_t01.dart
@@ -14,7 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 class C {
   C(late int x) {}                                //# 01: compile-time error
   C(int x, [late String y]) {}                    //# 02: compile-time error
diff --git a/LanguageFeatures/nnbd/static_errors_A17_t02.dart b/LanguageFeatures/nnbd/static_errors_A17_t02.dart
index b29bc38..603255f 100644
--- a/LanguageFeatures/nnbd/static_errors_A17_t02.dart
+++ b/LanguageFeatures/nnbd/static_errors_A17_t02.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 class A {}
 
 class C {
diff --git a/LanguageFeatures/nnbd/static_errors_A17_t03.dart b/LanguageFeatures/nnbd/static_errors_A17_t03.dart
index 1ee34f3..066a508 100644
--- a/LanguageFeatures/nnbd/static_errors_A17_t03.dart
+++ b/LanguageFeatures/nnbd/static_errors_A17_t03.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 void test() {}
 
 main() {
diff --git a/LanguageFeatures/nnbd/static_errors_A17_t04.dart b/LanguageFeatures/nnbd/static_errors_A17_t04.dart
index 5dbe2c4..e5ccdbc 100644
--- a/LanguageFeatures/nnbd/static_errors_A17_t04.dart
+++ b/LanguageFeatures/nnbd/static_errors_A17_t04.dart
@@ -14,7 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 main() {
   for (late int i = 0; i < 3; i++) {
 //     ^^^^
diff --git a/LanguageFeatures/nnbd/static_errors_A17_t05.dart b/LanguageFeatures/nnbd/static_errors_A17_t05.dart
index 3d07117..3a9aa2c 100644
--- a/LanguageFeatures/nnbd/static_errors_A17_t05.dart
+++ b/LanguageFeatures/nnbd/static_errors_A17_t05.dart
@@ -14,7 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 main() {
   var list = [3, 1, 4, 1, 5];
   for (late int i in list) {
diff --git a/LanguageFeatures/nnbd/static_errors_A17_t06.dart b/LanguageFeatures/nnbd/static_errors_A17_t06.dart
index a0dcfb9..e6ebb7c 100644
--- a/LanguageFeatures/nnbd/static_errors_A17_t06.dart
+++ b/LanguageFeatures/nnbd/static_errors_A17_t06.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "dart:async";
 
 main() async {
diff --git a/LanguageFeatures/nnbd/static_errors_A17_t07.dart b/LanguageFeatures/nnbd/static_errors_A17_t07.dart
index ba4e4dc..a1e62e0 100644
--- a/LanguageFeatures/nnbd/static_errors_A17_t07.dart
+++ b/LanguageFeatures/nnbd/static_errors_A17_t07.dart
@@ -14,7 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 main() async {
   List list = [1, 2, 3, 4];
   <int> [
diff --git a/LanguageFeatures/nnbd/static_errors_A18_t01.dart b/LanguageFeatures/nnbd/static_errors_A18_t01.dart
index 47d5be9..e0df066 100644
--- a/LanguageFeatures/nnbd/static_errors_A18_t01.dart
+++ b/LanguageFeatures/nnbd/static_errors_A18_t01.dart
@@ -13,6 +13,7 @@
  * @issue 39684
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 late final g;
diff --git a/LanguageFeatures/nnbd/static_errors_A18_t02.dart b/LanguageFeatures/nnbd/static_errors_A18_t02.dart
index 987f948..575285e 100644
--- a/LanguageFeatures/nnbd/static_errors_A18_t02.dart
+++ b/LanguageFeatures/nnbd/static_errors_A18_t02.dart
@@ -13,6 +13,7 @@
  * @issue 39684
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 late final g;
diff --git a/LanguageFeatures/nnbd/static_errors_A19_t01.dart b/LanguageFeatures/nnbd/static_errors_A19_t01.dart
index e0a5650..63b6840 100644
--- a/LanguageFeatures/nnbd/static_errors_A19_t01.dart
+++ b/LanguageFeatures/nnbd/static_errors_A19_t01.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 
 void init() {}
 main() {
diff --git a/LanguageFeatures/nnbd/static_errors_A19_t02.dart b/LanguageFeatures/nnbd/static_errors_A19_t02.dart
index c02c6ea..208dd4f 100644
--- a/LanguageFeatures/nnbd/static_errors_A19_t02.dart
+++ b/LanguageFeatures/nnbd/static_errors_A19_t02.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 
 class C {
 }
diff --git a/LanguageFeatures/nnbd/static_errors_A20_t01.dart b/LanguageFeatures/nnbd/static_errors_A20_t01.dart
index 54feca6..b29c83a 100644
--- a/LanguageFeatures/nnbd/static_errors_A20_t01.dart
+++ b/LanguageFeatures/nnbd/static_errors_A20_t01.dart
@@ -13,6 +13,7 @@
  * @issue 39598
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 class A {
   test() {}
 }
diff --git a/LanguageFeatures/nnbd/static_errors_A20_t02.dart b/LanguageFeatures/nnbd/static_errors_A20_t02.dart
index a03d1c4..c51529a 100644
--- a/LanguageFeatures/nnbd/static_errors_A20_t02.dart
+++ b/LanguageFeatures/nnbd/static_errors_A20_t02.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 class A {
   test() {}
 }
diff --git a/LanguageFeatures/nnbd/static_errors_A20_t03.dart b/LanguageFeatures/nnbd/static_errors_A20_t03.dart
index 89115d0..df4ec5a 100644
--- a/LanguageFeatures/nnbd/static_errors_A20_t03.dart
+++ b/LanguageFeatures/nnbd/static_errors_A20_t03.dart
@@ -13,6 +13,7 @@
  * @issue 39598
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
+// Requirements=nnbd-strong
 class A {
   test() {}
 }
diff --git a/LanguageFeatures/nnbd/static_errors_A20_t04.dart b/LanguageFeatures/nnbd/static_errors_A20_t04.dart
index 04cd792..4c39a08 100644
--- a/LanguageFeatures/nnbd/static_errors_A20_t04.dart
+++ b/LanguageFeatures/nnbd/static_errors_A20_t04.dart
@@ -13,6 +13,7 @@
  * @issue 39598
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "legacy_lib.dart";
 
 main() {
diff --git a/LanguageFeatures/nnbd/static_errors_A20_t05.dart b/LanguageFeatures/nnbd/static_errors_A20_t05.dart
index 0c70a08..e26536d 100644
--- a/LanguageFeatures/nnbd/static_errors_A20_t05.dart
+++ b/LanguageFeatures/nnbd/static_errors_A20_t05.dart
@@ -14,6 +14,7 @@
  * @issue 39714
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 void foo() {}
 void bar() {}
 
diff --git a/LanguageFeatures/nnbd/static_errors_A20_t06.dart b/LanguageFeatures/nnbd/static_errors_A20_t06.dart
index 9068030..8efc276 100644
--- a/LanguageFeatures/nnbd/static_errors_A20_t06.dart
+++ b/LanguageFeatures/nnbd/static_errors_A20_t06.dart
@@ -14,6 +14,7 @@
  * @issue 39714
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 void foo() {}
 void bar() {}
 typedef void Foo();
diff --git a/LanguageFeatures/nnbd/static_errors_A20_t07.dart b/LanguageFeatures/nnbd/static_errors_A20_t07.dart
index 9ffc849..6d5847f 100644
--- a/LanguageFeatures/nnbd/static_errors_A20_t07.dart
+++ b/LanguageFeatures/nnbd/static_errors_A20_t07.dart
@@ -14,7 +14,7 @@
  * @issue 39714
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 test<T extends Object>(T t) {
   t?.toString();                                  //# 01: static type warning
   t?..toString();                                 //# 02: static type warning
diff --git a/LanguageFeatures/nnbd/static_errors_A20_t08.dart b/LanguageFeatures/nnbd/static_errors_A20_t08.dart
index 646f4e7..cd44c85 100644
--- a/LanguageFeatures/nnbd/static_errors_A20_t08.dart
+++ b/LanguageFeatures/nnbd/static_errors_A20_t08.dart
@@ -14,6 +14,7 @@
  * @issue 39714
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "dart:async";
 
 test(FutureOr<Never> t) {
diff --git a/LanguageFeatures/nnbd/static_errors_A20_t09.dart b/LanguageFeatures/nnbd/static_errors_A20_t09.dart
index 6b7eba7..8577d77 100644
--- a/LanguageFeatures/nnbd/static_errors_A20_t09.dart
+++ b/LanguageFeatures/nnbd/static_errors_A20_t09.dart
@@ -14,6 +14,7 @@
  * @issue 39714
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "dart:async";
 
 void foo() {}
diff --git a/LanguageFeatures/nnbd/static_errors_A20_t10.dart b/LanguageFeatures/nnbd/static_errors_A20_t10.dart
index 41905c8..00820f2 100644
--- a/LanguageFeatures/nnbd/static_errors_A20_t10.dart
+++ b/LanguageFeatures/nnbd/static_errors_A20_t10.dart
@@ -14,6 +14,7 @@
  * @issue 39714
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "dart:async";
 import "legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/static_errors_A20_t11.dart b/LanguageFeatures/nnbd/static_errors_A20_t11.dart
index a893eda..3052ac6 100644
--- a/LanguageFeatures/nnbd/static_errors_A20_t11.dart
+++ b/LanguageFeatures/nnbd/static_errors_A20_t11.dart
@@ -14,6 +14,7 @@
  * @issue 39714
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "dart:async";
 
 test<T extends Object>(FutureOr<T> t) {
diff --git a/LanguageFeatures/nnbd/static_errors_A20_t12.dart b/LanguageFeatures/nnbd/static_errors_A20_t12.dart
index f016370..bdeae70 100644
--- a/LanguageFeatures/nnbd/static_errors_A20_t12.dart
+++ b/LanguageFeatures/nnbd/static_errors_A20_t12.dart
@@ -14,6 +14,7 @@
  * @issue 39714
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "dart:async";
 
 class A {}
diff --git a/LanguageFeatures/nnbd/static_errors_A20_t13.dart b/LanguageFeatures/nnbd/static_errors_A20_t13.dart
index 814921d..7a0e118 100644
--- a/LanguageFeatures/nnbd/static_errors_A20_t13.dart
+++ b/LanguageFeatures/nnbd/static_errors_A20_t13.dart
@@ -14,6 +14,7 @@
  * @issue 39714
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 class A {
 }
 class C extends A {}
diff --git a/LanguageFeatures/nnbd/static_errors_A20_t14.dart b/LanguageFeatures/nnbd/static_errors_A20_t14.dart
index 5a6d9eb..4a297be 100644
--- a/LanguageFeatures/nnbd/static_errors_A20_t14.dart
+++ b/LanguageFeatures/nnbd/static_errors_A20_t14.dart
@@ -14,6 +14,7 @@
  * @issue 39714
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 class A {
 }
 class C extends A {}
diff --git a/LanguageFeatures/nnbd/static_errors_A21_t01.dart b/LanguageFeatures/nnbd/static_errors_A21_t01.dart
index eb1832b..716f69c 100644
--- a/LanguageFeatures/nnbd/static_errors_A21_t01.dart
+++ b/LanguageFeatures/nnbd/static_errors_A21_t01.dart
@@ -17,7 +17,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 main() {
   Null v = null;
   v = null;
diff --git a/LanguageFeatures/nnbd/static_errors_A21_t02.dart b/LanguageFeatures/nnbd/static_errors_A21_t02.dart
index 6677985..84a5001 100644
--- a/LanguageFeatures/nnbd/static_errors_A21_t02.dart
+++ b/LanguageFeatures/nnbd/static_errors_A21_t02.dart
@@ -18,6 +18,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 class C {}
 
 main() {
diff --git a/LanguageFeatures/nnbd/static_errors_A21_t03.dart b/LanguageFeatures/nnbd/static_errors_A21_t03.dart
index 8148d13..eda0cf8 100644
--- a/LanguageFeatures/nnbd/static_errors_A21_t03.dart
+++ b/LanguageFeatures/nnbd/static_errors_A21_t03.dart
@@ -18,6 +18,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
+// Requirements=nnbd-strong
 class C {}
 
 typedef CAlias = C?;
diff --git a/LanguageFeatures/nnbd/static_errors_A21_t04.dart b/LanguageFeatures/nnbd/static_errors_A21_t04.dart
index 7d5bd0f..b4430a4 100644
--- a/LanguageFeatures/nnbd/static_errors_A21_t04.dart
+++ b/LanguageFeatures/nnbd/static_errors_A21_t04.dart
@@ -18,6 +18,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "legacy_lib.dart";
 
 main() {
diff --git a/LanguageFeatures/nnbd/static_errors_A21_t06.dart b/LanguageFeatures/nnbd/static_errors_A21_t06.dart
index 46af46a..47a8843 100644
--- a/LanguageFeatures/nnbd/static_errors_A21_t06.dart
+++ b/LanguageFeatures/nnbd/static_errors_A21_t06.dart
@@ -18,6 +18,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "dart:async";
 
 class C {}
diff --git a/LanguageFeatures/nnbd/static_errors_A21_t07.dart b/LanguageFeatures/nnbd/static_errors_A21_t07.dart
index 0cb90be..1db6d80 100644
--- a/LanguageFeatures/nnbd/static_errors_A21_t07.dart
+++ b/LanguageFeatures/nnbd/static_errors_A21_t07.dart
@@ -18,6 +18,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
+// Requirements=nnbd-strong
 import "dart:async";
 
 class C {}
diff --git a/LanguageFeatures/nnbd/static_errors_A21_t08.dart b/LanguageFeatures/nnbd/static_errors_A21_t08.dart
index b55e4de..a8569fc 100644
--- a/LanguageFeatures/nnbd/static_errors_A21_t08.dart
+++ b/LanguageFeatures/nnbd/static_errors_A21_t08.dart
@@ -18,6 +18,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "dart:async";
 import "legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/static_errors_A21_t09.dart b/LanguageFeatures/nnbd/static_errors_A21_t09.dart
index d475521..9a2c24d 100644
--- a/LanguageFeatures/nnbd/static_errors_A21_t09.dart
+++ b/LanguageFeatures/nnbd/static_errors_A21_t09.dart
@@ -17,6 +17,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 
 main() {
   dynamic d1 = null;
diff --git a/LanguageFeatures/nnbd/static_errors_A21_t10.dart b/LanguageFeatures/nnbd/static_errors_A21_t10.dart
index ef0ecb3..87e3177 100644
--- a/LanguageFeatures/nnbd/static_errors_A21_t10.dart
+++ b/LanguageFeatures/nnbd/static_errors_A21_t10.dart
@@ -17,6 +17,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 
 void test() {}
 
diff --git a/LanguageFeatures/nnbd/static_errors_A22_t01.dart b/LanguageFeatures/nnbd/static_errors_A22_t01.dart
index 31549ec..ba1bd74 100644
--- a/LanguageFeatures/nnbd/static_errors_A22_t01.dart
+++ b/LanguageFeatures/nnbd/static_errors_A22_t01.dart
@@ -19,6 +19,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 
 dynamic test() => new Object();
 
diff --git a/LanguageFeatures/nnbd/static_errors_A22_t02.dart b/LanguageFeatures/nnbd/static_errors_A22_t02.dart
index e46a135..611a43e 100644
--- a/LanguageFeatures/nnbd/static_errors_A22_t02.dart
+++ b/LanguageFeatures/nnbd/static_errors_A22_t02.dart
@@ -19,6 +19,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 
 void foo() {}
 typedef void bar(int i);
diff --git a/LanguageFeatures/nnbd/static_errors_A22_t03.dart b/LanguageFeatures/nnbd/static_errors_A22_t03.dart
index e476e54..8613bde 100644
--- a/LanguageFeatures/nnbd/static_errors_A22_t03.dart
+++ b/LanguageFeatures/nnbd/static_errors_A22_t03.dart
@@ -19,6 +19,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 
 abstract class A {
   void foo(int i);
diff --git a/LanguageFeatures/nnbd/static_errors_A22_t04.dart b/LanguageFeatures/nnbd/static_errors_A22_t04.dart
index b2886cb..a1a6cda 100644
--- a/LanguageFeatures/nnbd/static_errors_A22_t04.dart
+++ b/LanguageFeatures/nnbd/static_errors_A22_t04.dart
@@ -19,7 +19,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
-
+// Requirements=nnbd-strong
 abstract class A {
   void foo(int i);
 }
diff --git a/LanguageFeatures/nnbd/static_errors_A22_t05.dart b/LanguageFeatures/nnbd/static_errors_A22_t05.dart
index 64eaecc..c282c2c 100644
--- a/LanguageFeatures/nnbd/static_errors_A22_t05.dart
+++ b/LanguageFeatures/nnbd/static_errors_A22_t05.dart
@@ -19,6 +19,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "legacy_lib.dart";
 
 main() {
diff --git a/LanguageFeatures/nnbd/static_errors_A22_t06.dart b/LanguageFeatures/nnbd/static_errors_A22_t06.dart
index dbfbdd2..559cdce 100644
--- a/LanguageFeatures/nnbd/static_errors_A22_t06.dart
+++ b/LanguageFeatures/nnbd/static_errors_A22_t06.dart
@@ -20,6 +20,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
+// Requirements=nnbd-strong
 import "legacy_lib.dart";
 
 typedef SAlias = S;
diff --git a/LanguageFeatures/nnbd/static_errors_A22_t09.dart b/LanguageFeatures/nnbd/static_errors_A22_t09.dart
index feaccae..1601134 100644
--- a/LanguageFeatures/nnbd/static_errors_A22_t09.dart
+++ b/LanguageFeatures/nnbd/static_errors_A22_t09.dart
@@ -19,6 +19,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "dart:async";
 
 class C {
diff --git a/LanguageFeatures/nnbd/static_errors_A22_t10.dart b/LanguageFeatures/nnbd/static_errors_A22_t10.dart
index bb3f0a5..ff31bc2 100644
--- a/LanguageFeatures/nnbd/static_errors_A22_t10.dart
+++ b/LanguageFeatures/nnbd/static_errors_A22_t10.dart
@@ -20,6 +20,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
+// Requirements=nnbd-strong
 import "dart:async";
 
 class C {
diff --git a/LanguageFeatures/nnbd/static_errors_A22_t11.dart b/LanguageFeatures/nnbd/static_errors_A22_t11.dart
index 7cd4012..f8ff5b5 100644
--- a/LanguageFeatures/nnbd/static_errors_A22_t11.dart
+++ b/LanguageFeatures/nnbd/static_errors_A22_t11.dart
@@ -20,6 +20,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "dart:async";
 import "legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/static_errors_A22_t12.dart b/LanguageFeatures/nnbd/static_errors_A22_t12.dart
index 3053473..ec14502 100644
--- a/LanguageFeatures/nnbd/static_errors_A22_t12.dart
+++ b/LanguageFeatures/nnbd/static_errors_A22_t12.dart
@@ -20,6 +20,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
+// Requirements=nnbd-strong
 import "dart:async";
 import "legacy_library_aliases_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/static_errors_A22_t13.dart b/LanguageFeatures/nnbd/static_errors_A22_t13.dart
index 4174d0b..f15439b 100644
--- a/LanguageFeatures/nnbd/static_errors_A22_t13.dart
+++ b/LanguageFeatures/nnbd/static_errors_A22_t13.dart
@@ -19,7 +19,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 class S {}
 
 class C<T extends S> {
diff --git a/LanguageFeatures/nnbd/static_errors_A22_t14.dart b/LanguageFeatures/nnbd/static_errors_A22_t14.dart
index 3d23602..070647d 100644
--- a/LanguageFeatures/nnbd/static_errors_A22_t14.dart
+++ b/LanguageFeatures/nnbd/static_errors_A22_t14.dart
@@ -20,7 +20,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
-
+// Requirements=nnbd-strong
 class S {}
 
 typedef SAlias = S;
diff --git a/LanguageFeatures/nnbd/static_errors_A22_t15.dart b/LanguageFeatures/nnbd/static_errors_A22_t15.dart
index c6815d8..c6dd932 100644
--- a/LanguageFeatures/nnbd/static_errors_A22_t15.dart
+++ b/LanguageFeatures/nnbd/static_errors_A22_t15.dart
@@ -20,6 +20,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "legacy_lib.dart";
 
 class C<X extends A> {
diff --git a/LanguageFeatures/nnbd/static_errors_A22_t16.dart b/LanguageFeatures/nnbd/static_errors_A22_t16.dart
index 3735cf2..64dfa89 100644
--- a/LanguageFeatures/nnbd/static_errors_A22_t16.dart
+++ b/LanguageFeatures/nnbd/static_errors_A22_t16.dart
@@ -19,7 +19,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 class S {}
 
 dynamic getDynamic(dynamic v) => v;
diff --git a/LanguageFeatures/nnbd/static_errors_A22_t17.dart b/LanguageFeatures/nnbd/static_errors_A22_t17.dart
index 0b270be..464a140 100644
--- a/LanguageFeatures/nnbd/static_errors_A22_t17.dart
+++ b/LanguageFeatures/nnbd/static_errors_A22_t17.dart
@@ -20,7 +20,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
-
+// Requirements=nnbd-strong
 class S {}
 
 typedef SAlias = S;
diff --git a/LanguageFeatures/nnbd/static_errors_A22_t18.dart b/LanguageFeatures/nnbd/static_errors_A22_t18.dart
index 8acceb1..a63e2ec 100644
--- a/LanguageFeatures/nnbd/static_errors_A22_t18.dart
+++ b/LanguageFeatures/nnbd/static_errors_A22_t18.dart
@@ -19,6 +19,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "legacy_lib.dart";
 
 class S extends A {}
diff --git a/LanguageFeatures/nnbd/static_errors_A22_t19.dart b/LanguageFeatures/nnbd/static_errors_A22_t19.dart
index c53cdd1..5f5c1ae 100644
--- a/LanguageFeatures/nnbd/static_errors_A22_t19.dart
+++ b/LanguageFeatures/nnbd/static_errors_A22_t19.dart
@@ -19,6 +19,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
+// Requirements=nnbd-strong
 import "legacy_library_aliases_lib.dart";
 
 class S extends AAlias {}
diff --git a/LanguageFeatures/nnbd/static_errors_A23_t01.dart b/LanguageFeatures/nnbd/static_errors_A23_t01.dart
index 72d4bb0..3cddc9c 100644
--- a/LanguageFeatures/nnbd/static_errors_A23_t01.dart
+++ b/LanguageFeatures/nnbd/static_errors_A23_t01.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 class A {}
 class B {}
 
diff --git a/LanguageFeatures/nnbd/static_errors_A23_t02.dart b/LanguageFeatures/nnbd/static_errors_A23_t02.dart
index 25ad4e5..2c8823c 100644
--- a/LanguageFeatures/nnbd/static_errors_A23_t02.dart
+++ b/LanguageFeatures/nnbd/static_errors_A23_t02.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
+// Requirements=nnbd-strong
 class A {}
 class B {}
 
diff --git a/LanguageFeatures/nnbd/static_errors_A24_t01.dart b/LanguageFeatures/nnbd/static_errors_A24_t01.dart
index 5e618f9..468a1b0 100644
--- a/LanguageFeatures/nnbd/static_errors_A24_t01.dart
+++ b/LanguageFeatures/nnbd/static_errors_A24_t01.dart
@@ -13,6 +13,7 @@
  * @issue 39661
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "dart:async";
 
 class C {
diff --git a/LanguageFeatures/nnbd/static_errors_A24_t02.dart b/LanguageFeatures/nnbd/static_errors_A24_t02.dart
index 891c834..004fca2 100644
--- a/LanguageFeatures/nnbd/static_errors_A24_t02.dart
+++ b/LanguageFeatures/nnbd/static_errors_A24_t02.dart
@@ -13,6 +13,7 @@
  * @issue 39661
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "dart:async";
 
 class C {
diff --git a/LanguageFeatures/nnbd/static_errors_A25_t01.dart b/LanguageFeatures/nnbd/static_errors_A25_t01.dart
index a5c136d..c9a4127 100644
--- a/LanguageFeatures/nnbd/static_errors_A25_t01.dart
+++ b/LanguageFeatures/nnbd/static_errors_A25_t01.dart
@@ -13,7 +13,7 @@
  * @issue 39681
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 class C {
   static late final int s = 42;
 //       ^^^^
diff --git a/LanguageFeatures/nnbd/static_errors_A26_t01.dart b/LanguageFeatures/nnbd/static_errors_A26_t01.dart
index 29a2ffe..a28c51b 100644
--- a/LanguageFeatures/nnbd/static_errors_A26_t01.dart
+++ b/LanguageFeatures/nnbd/static_errors_A26_t01.dart
@@ -15,7 +15,7 @@
  * @issue 39712
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 class A {
   A() {}
 
diff --git a/LanguageFeatures/nnbd/static_errors_A27_t01.dart b/LanguageFeatures/nnbd/static_errors_A27_t01.dart
index 9c3bf85..5e7f25d 100644
--- a/LanguageFeatures/nnbd/static_errors_A27_t01.dart
+++ b/LanguageFeatures/nnbd/static_errors_A27_t01.dart
@@ -13,7 +13,7 @@
  * @issue 39598
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 test (Never n) {
   n!;             //# 01: static type warning
 }
diff --git a/LanguageFeatures/nnbd/static_errors_A27_t02.dart b/LanguageFeatures/nnbd/static_errors_A27_t02.dart
index 1be047b..fb87aa3 100644
--- a/LanguageFeatures/nnbd/static_errors_A27_t02.dart
+++ b/LanguageFeatures/nnbd/static_errors_A27_t02.dart
@@ -13,7 +13,7 @@
  * @issue 39598
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 void foo() {}
 typedef void Foo();
 
diff --git a/LanguageFeatures/nnbd/static_errors_A27_t03.dart b/LanguageFeatures/nnbd/static_errors_A27_t03.dart
index 6d11e89..b237dd1 100644
--- a/LanguageFeatures/nnbd/static_errors_A27_t03.dart
+++ b/LanguageFeatures/nnbd/static_errors_A27_t03.dart
@@ -13,7 +13,7 @@
  * @issue 39598
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 class A {}
 
 main() {
diff --git a/LanguageFeatures/nnbd/static_errors_A27_t04.dart b/LanguageFeatures/nnbd/static_errors_A27_t04.dart
index 31843e1..d3fa001 100644
--- a/LanguageFeatures/nnbd/static_errors_A27_t04.dart
+++ b/LanguageFeatures/nnbd/static_errors_A27_t04.dart
@@ -13,6 +13,7 @@
  * @issue 39598
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "legacy_lib.dart";
 
 main() {
diff --git a/LanguageFeatures/nnbd/static_errors_A27_t05.dart b/LanguageFeatures/nnbd/static_errors_A27_t05.dart
index 29f2a46..3b23065 100644
--- a/LanguageFeatures/nnbd/static_errors_A27_t05.dart
+++ b/LanguageFeatures/nnbd/static_errors_A27_t05.dart
@@ -13,7 +13,7 @@
  * @issue 39598
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 test<T extends Object>(T t) {
   t!;     //# 01: static type warning
 }
diff --git a/LanguageFeatures/nnbd/static_errors_A27_t06.dart b/LanguageFeatures/nnbd/static_errors_A27_t06.dart
index 76896be..5b6344c 100644
--- a/LanguageFeatures/nnbd/static_errors_A27_t06.dart
+++ b/LanguageFeatures/nnbd/static_errors_A27_t06.dart
@@ -14,7 +14,7 @@
  * @issue 39867
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 class A {}
 
 main() {
diff --git a/LanguageFeatures/nnbd/static_errors_A27_t07.dart b/LanguageFeatures/nnbd/static_errors_A27_t07.dart
index 2877a5b..b48eeb0 100644
--- a/LanguageFeatures/nnbd/static_errors_A27_t07.dart
+++ b/LanguageFeatures/nnbd/static_errors_A27_t07.dart
@@ -14,7 +14,7 @@
  * @issue 39867
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 class A {}
 
 main() {
diff --git a/LanguageFeatures/nnbd/static_errors_A27_t08.dart b/LanguageFeatures/nnbd/static_errors_A27_t08.dart
index e45fab3..7a4c3fe 100644
--- a/LanguageFeatures/nnbd/static_errors_A27_t08.dart
+++ b/LanguageFeatures/nnbd/static_errors_A27_t08.dart
@@ -13,6 +13,7 @@
  * @issue 39598
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "dart:async";
 
 test(FutureOr<Never> n) {
diff --git a/LanguageFeatures/nnbd/static_errors_A27_t09.dart b/LanguageFeatures/nnbd/static_errors_A27_t09.dart
index 291b77d..21244c2 100644
--- a/LanguageFeatures/nnbd/static_errors_A27_t09.dart
+++ b/LanguageFeatures/nnbd/static_errors_A27_t09.dart
@@ -13,6 +13,7 @@
  * @issue 39598
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "dart:async";
 
 void foo() {}
diff --git a/LanguageFeatures/nnbd/static_errors_A27_t10.dart b/LanguageFeatures/nnbd/static_errors_A27_t10.dart
index 353892f..cddf678 100644
--- a/LanguageFeatures/nnbd/static_errors_A27_t10.dart
+++ b/LanguageFeatures/nnbd/static_errors_A27_t10.dart
@@ -13,6 +13,7 @@
  * @issue 39598
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "dart:async";
 
 class A {}
diff --git a/LanguageFeatures/nnbd/static_errors_A27_t11.dart b/LanguageFeatures/nnbd/static_errors_A27_t11.dart
index 7ab9f9a..6eeaa15 100644
--- a/LanguageFeatures/nnbd/static_errors_A27_t11.dart
+++ b/LanguageFeatures/nnbd/static_errors_A27_t11.dart
@@ -13,6 +13,7 @@
  * @issue 39598
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "dart:async";
 import "legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/static_errors_A27_t12.dart b/LanguageFeatures/nnbd/static_errors_A27_t12.dart
index 57a5cc0..16f5181 100644
--- a/LanguageFeatures/nnbd/static_errors_A27_t12.dart
+++ b/LanguageFeatures/nnbd/static_errors_A27_t12.dart
@@ -13,6 +13,7 @@
  * @issue 39598
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "dart:async";
 
 class A {}
diff --git a/LanguageFeatures/nnbd/syntax_A01_t01.dart b/LanguageFeatures/nnbd/syntax_A01_t01.dart
index 9d98753..cc170ad 100644
--- a/LanguageFeatures/nnbd/syntax_A01_t01.dart
+++ b/LanguageFeatures/nnbd/syntax_A01_t01.dart
@@ -12,7 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 class A {}
 
 class C<X extends A?> {
diff --git a/LanguageFeatures/nnbd/syntax_A01_t02.dart b/LanguageFeatures/nnbd/syntax_A01_t02.dart
index 1c80f9c..3cfc621 100644
--- a/LanguageFeatures/nnbd/syntax_A01_t02.dart
+++ b/LanguageFeatures/nnbd/syntax_A01_t02.dart
@@ -12,7 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 dynamic? foo(dynamic? d) => d;
 
 void? bar(void? v) => v;
diff --git a/LanguageFeatures/nnbd/syntax_A01_t03.dart b/LanguageFeatures/nnbd/syntax_A01_t03.dart
index 9eef89d..07e077d 100644
--- a/LanguageFeatures/nnbd/syntax_A01_t03.dart
+++ b/LanguageFeatures/nnbd/syntax_A01_t03.dart
@@ -12,7 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 typedef void foo();
 
 foo? bar(foo? v) => v;
diff --git a/LanguageFeatures/nnbd/syntax_A01_t04.dart b/LanguageFeatures/nnbd/syntax_A01_t04.dart
index 9ed1d42..b3a10c7 100644
--- a/LanguageFeatures/nnbd/syntax_A01_t04.dart
+++ b/LanguageFeatures/nnbd/syntax_A01_t04.dart
@@ -12,7 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
-
+// Requirements=nnbd-strong
 class A {}
 
 class C<X extends A?> {
diff --git a/LanguageFeatures/nnbd/syntax_A01_t05.dart b/LanguageFeatures/nnbd/syntax_A01_t05.dart
index e9c1411..36c33c2 100644
--- a/LanguageFeatures/nnbd/syntax_A01_t05.dart
+++ b/LanguageFeatures/nnbd/syntax_A01_t05.dart
@@ -12,6 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 int ? testInt(int ? i) => i == null ? i ?? 0 : i;
diff --git a/LanguageFeatures/nnbd/syntax_A01_t06.dart b/LanguageFeatures/nnbd/syntax_A01_t06.dart
index 5706eb7..0706d55 100644
--- a/LanguageFeatures/nnbd/syntax_A01_t06.dart
+++ b/LanguageFeatures/nnbd/syntax_A01_t06.dart
@@ -12,7 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 Never? foo(Never? n) => n;
 
 main() {
diff --git a/LanguageFeatures/nnbd/syntax_A02_t01.dart b/LanguageFeatures/nnbd/syntax_A02_t01.dart
index e19204a..32de333 100644
--- a/LanguageFeatures/nnbd/syntax_A02_t01.dart
+++ b/LanguageFeatures/nnbd/syntax_A02_t01.dart
@@ -11,6 +11,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 Never fail() {
   throw new Exception();
 }
diff --git a/LanguageFeatures/nnbd/syntax_A02_t02.dart b/LanguageFeatures/nnbd/syntax_A02_t02.dart
index 7365308..e775a3b 100644
--- a/LanguageFeatures/nnbd/syntax_A02_t02.dart
+++ b/LanguageFeatures/nnbd/syntax_A02_t02.dart
@@ -11,7 +11,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
-
+// Requirements=nnbd-strong
 typedef Neverland = Never;
 
 Neverland fail() {
diff --git a/LanguageFeatures/nnbd/syntax_A02_t03.dart b/LanguageFeatures/nnbd/syntax_A02_t03.dart
index 926c0f7..62a9540 100644
--- a/LanguageFeatures/nnbd/syntax_A02_t03.dart
+++ b/LanguageFeatures/nnbd/syntax_A02_t03.dart
@@ -11,6 +11,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 main() {
diff --git a/LanguageFeatures/nnbd/syntax_A02_t04.dart b/LanguageFeatures/nnbd/syntax_A02_t04.dart
index 0c95e38..97bf36d 100644
--- a/LanguageFeatures/nnbd/syntax_A02_t04.dart
+++ b/LanguageFeatures/nnbd/syntax_A02_t04.dart
@@ -11,6 +11,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 typedef Neverland = Never;
diff --git a/LanguageFeatures/nnbd/syntax_A03_t01.dart b/LanguageFeatures/nnbd/syntax_A03_t01.dart
index 0b33159..401b7e9 100644
--- a/LanguageFeatures/nnbd/syntax_A03_t01.dart
+++ b/LanguageFeatures/nnbd/syntax_A03_t01.dart
@@ -11,6 +11,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {}
diff --git a/LanguageFeatures/nnbd/syntax_A03_t02.dart b/LanguageFeatures/nnbd/syntax_A03_t02.dart
index d1a79b5..67563b0 100644
--- a/LanguageFeatures/nnbd/syntax_A03_t02.dart
+++ b/LanguageFeatures/nnbd/syntax_A03_t02.dart
@@ -12,7 +12,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
-
+// Requirements=nnbd-strong
 class C {}
 
 typedef CAlias = C?;
diff --git a/LanguageFeatures/nnbd/syntax_A04_t01.dart b/LanguageFeatures/nnbd/syntax_A04_t01.dart
index a29e527..e823340 100644
--- a/LanguageFeatures/nnbd/syntax_A04_t01.dart
+++ b/LanguageFeatures/nnbd/syntax_A04_t01.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class A {
diff --git a/LanguageFeatures/nnbd/syntax_A05_t01.dart b/LanguageFeatures/nnbd/syntax_A05_t01.dart
index d9e54d3..0073e1e 100644
--- a/LanguageFeatures/nnbd/syntax_A05_t01.dart
+++ b/LanguageFeatures/nnbd/syntax_A05_t01.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class A {}
diff --git a/LanguageFeatures/nnbd/syntax_A05_t02.dart b/LanguageFeatures/nnbd/syntax_A05_t02.dart
index 99db959..3001ec7 100644
--- a/LanguageFeatures/nnbd/syntax_A05_t02.dart
+++ b/LanguageFeatures/nnbd/syntax_A05_t02.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class A {}
diff --git a/LanguageFeatures/nnbd/syntax_A05_t03.dart b/LanguageFeatures/nnbd/syntax_A05_t03.dart
index 7d50aa4..d6e7b28 100644
--- a/LanguageFeatures/nnbd/syntax_A05_t03.dart
+++ b/LanguageFeatures/nnbd/syntax_A05_t03.dart
@@ -15,6 +15,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class A {}
diff --git a/LanguageFeatures/nnbd/syntax_A05_t04.dart b/LanguageFeatures/nnbd/syntax_A05_t04.dart
index b86448e..7892e6a 100644
--- a/LanguageFeatures/nnbd/syntax_A05_t04.dart
+++ b/LanguageFeatures/nnbd/syntax_A05_t04.dart
@@ -14,7 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 class A {}
 
 class C {
diff --git a/LanguageFeatures/nnbd/syntax_A05_t05.dart b/LanguageFeatures/nnbd/syntax_A05_t05.dart
index 50e3302..01f93d6 100644
--- a/LanguageFeatures/nnbd/syntax_A05_t05.dart
+++ b/LanguageFeatures/nnbd/syntax_A05_t05.dart
@@ -14,7 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 class A {}
 
 typedef String Foo1(required int x, {String z, required String y});
diff --git a/LanguageFeatures/nnbd/syntax_A05_t06.dart b/LanguageFeatures/nnbd/syntax_A05_t06.dart
index e357085..323ee14 100644
--- a/LanguageFeatures/nnbd/syntax_A05_t06.dart
+++ b/LanguageFeatures/nnbd/syntax_A05_t06.dart
@@ -15,6 +15,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class A {}
diff --git a/LanguageFeatures/nnbd/syntax_A06_t01.dart b/LanguageFeatures/nnbd/syntax_A06_t01.dart
index 741c609..4c13e57 100644
--- a/LanguageFeatures/nnbd/syntax_A06_t01.dart
+++ b/LanguageFeatures/nnbd/syntax_A06_t01.dart
@@ -15,6 +15,7 @@
  * @issue 39865
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/syntax_A06_t02.dart b/LanguageFeatures/nnbd/syntax_A06_t02.dart
index 8f4e40b..ec4c860 100644
--- a/LanguageFeatures/nnbd/syntax_A06_t02.dart
+++ b/LanguageFeatures/nnbd/syntax_A06_t02.dart
@@ -14,6 +14,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 class C {
diff --git a/LanguageFeatures/nnbd/syntax_A06_t03.dart b/LanguageFeatures/nnbd/syntax_A06_t03.dart
index 7a38a60..522ace5 100644
--- a/LanguageFeatures/nnbd/syntax_A06_t03.dart
+++ b/LanguageFeatures/nnbd/syntax_A06_t03.dart
@@ -16,6 +16,7 @@
  * @issue 39865
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/syntax_A06_t04.dart b/LanguageFeatures/nnbd/syntax_A06_t04.dart
index a8aa636..ef0e1ca 100644
--- a/LanguageFeatures/nnbd/syntax_A06_t04.dart
+++ b/LanguageFeatures/nnbd/syntax_A06_t04.dart
@@ -15,6 +15,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "legacy_library_aliases_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/syntax_A07_t01.dart b/LanguageFeatures/nnbd/syntax_A07_t01.dart
index bbb97a9..4760cb9 100644
--- a/LanguageFeatures/nnbd/syntax_A07_t01.dart
+++ b/LanguageFeatures/nnbd/syntax_A07_t01.dart
@@ -16,7 +16,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 class A {}
 
 class C<X extends A??> {}
diff --git a/LanguageFeatures/nnbd/syntax_A07_t02.dart b/LanguageFeatures/nnbd/syntax_A07_t02.dart
index 11f35b1..2c4bdd5 100644
--- a/LanguageFeatures/nnbd/syntax_A07_t02.dart
+++ b/LanguageFeatures/nnbd/syntax_A07_t02.dart
@@ -16,7 +16,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
-
+// Requirements=nnbd-strong
 class A {}
 
 typedef AAlias = A;
diff --git a/LanguageFeatures/nnbd/syntax_A07_t03.dart b/LanguageFeatures/nnbd/syntax_A07_t03.dart
index 0137596..80a8431 100644
--- a/LanguageFeatures/nnbd/syntax_A07_t03.dart
+++ b/LanguageFeatures/nnbd/syntax_A07_t03.dart
@@ -16,6 +16,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "legacy_lib.dart";
 
 class B<X extends A??> {}
diff --git a/LanguageFeatures/nnbd/syntax_A07_t04.dart b/LanguageFeatures/nnbd/syntax_A07_t04.dart
index 2fd7f9b..e3a9379 100644
--- a/LanguageFeatures/nnbd/syntax_A07_t04.dart
+++ b/LanguageFeatures/nnbd/syntax_A07_t04.dart
@@ -16,6 +16,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
+// Requirements=nnbd-strong
 import "legacy_library_aliases_lib.dart";
 
 typedef AAlias2 = A??;
diff --git a/LanguageFeatures/nnbd/syntax_A07_t05.dart b/LanguageFeatures/nnbd/syntax_A07_t05.dart
index 001751d..0366914 100644
--- a/LanguageFeatures/nnbd/syntax_A07_t05.dart
+++ b/LanguageFeatures/nnbd/syntax_A07_t05.dart
@@ -16,6 +16,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 class A {}
 
 class C<T> {
diff --git a/LanguageFeatures/nnbd/syntax_A07_t06.dart b/LanguageFeatures/nnbd/syntax_A07_t06.dart
index e4fa12d..952e2d7 100644
--- a/LanguageFeatures/nnbd/syntax_A07_t06.dart
+++ b/LanguageFeatures/nnbd/syntax_A07_t06.dart
@@ -16,6 +16,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable,nonfunction-type-aliases
+// Requirements=nnbd-strong
 class A {}
 
 typedef AAlias1 = A?;
diff --git a/LanguageFeatures/nnbd/syntax_A08_t01.dart b/LanguageFeatures/nnbd/syntax_A08_t01.dart
index 73f8433..7d50a69 100644
--- a/LanguageFeatures/nnbd/syntax_A08_t01.dart
+++ b/LanguageFeatures/nnbd/syntax_A08_t01.dart
@@ -19,6 +19,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 
 main() {
diff --git a/LanguageFeatures/nnbd/type_reification_A01_t01.dart b/LanguageFeatures/nnbd/type_reification_A01_t01.dart
index 8ca1c0e..6279d08 100644
--- a/LanguageFeatures/nnbd/type_reification_A01_t01.dart
+++ b/LanguageFeatures/nnbd/type_reification_A01_t01.dart
@@ -10,7 +10,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "type_reification_legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/type_reification_A01_t02.dart b/LanguageFeatures/nnbd/type_reification_A01_t02.dart
index debf412..5b6a151 100644
--- a/LanguageFeatures/nnbd/type_reification_A01_t02.dart
+++ b/LanguageFeatures/nnbd/type_reification_A01_t02.dart
@@ -10,7 +10,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "type_reification_legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/type_reification_A01_t03.dart b/LanguageFeatures/nnbd/type_reification_A01_t03.dart
index c098f2a..44dd22a 100644
--- a/LanguageFeatures/nnbd/type_reification_A01_t03.dart
+++ b/LanguageFeatures/nnbd/type_reification_A01_t03.dart
@@ -10,7 +10,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "type_reification_legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/type_reification_A01_t04.dart b/LanguageFeatures/nnbd/type_reification_A01_t04.dart
index f7e36de..7d2fc75 100644
--- a/LanguageFeatures/nnbd/type_reification_A01_t04.dart
+++ b/LanguageFeatures/nnbd/type_reification_A01_t04.dart
@@ -10,7 +10,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "type_reification_legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/type_reification_A01_t05.dart b/LanguageFeatures/nnbd/type_reification_A01_t05.dart
index cfb0e10..0a1e1ed 100644
--- a/LanguageFeatures/nnbd/type_reification_A01_t05.dart
+++ b/LanguageFeatures/nnbd/type_reification_A01_t05.dart
@@ -10,7 +10,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "type_reification_legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/type_reification_A01_t06.dart b/LanguageFeatures/nnbd/type_reification_A01_t06.dart
index c9702aa..1fe4f21 100644
--- a/LanguageFeatures/nnbd/type_reification_A01_t06.dart
+++ b/LanguageFeatures/nnbd/type_reification_A01_t06.dart
@@ -10,7 +10,7 @@
  * @author iarkh@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-
+// Requirements=nnbd-strong
 import "../../Utils/expect.dart";
 import "type_reification_legacy_lib.dart";
 
diff --git a/LanguageFeatures/nnbd/type_reification_legacy_lib.dart b/LanguageFeatures/nnbd/type_reification_legacy_lib.dart
index 9d5c6b1..65cc30a 100644
--- a/LanguageFeatures/nnbd/type_reification_legacy_lib.dart
+++ b/LanguageFeatures/nnbd/type_reification_legacy_lib.dart
@@ -7,7 +7,7 @@
  * @author sgrekhov@unipro.ru
  */
 // SharedOptions=--enable-experiment=non-nullable
-// @dart=2.4
+// @dart=2.6
 
 library type_reification_legacy_lib;