diff --git a/pkg/analysis_server/lib/src/services/correction/assist_internal.dart b/pkg/analysis_server/lib/src/services/correction/assist_internal.dart
index 42230fe..b5a1027 100644
--- a/pkg/analysis_server/lib/src/services/correction/assist_internal.dart
+++ b/pkg/analysis_server/lib/src/services/correction/assist_internal.dart
@@ -180,15 +180,13 @@
       return assists;
     }
 
-    var context = CorrectionProducerContext(
+    var context = CorrectionProducerContext.create(
       selectionOffset: selectionOffset,
       selectionLength: selectionLength,
       resolvedResult: resolvedResult,
       workspace: workspace,
     );
-
-    var setupSuccess = context.setupCompute();
-    if (!setupSuccess) {
+    if (context == null) {
       return assists;
     }
 
@@ -233,16 +231,14 @@
   }
 
   Future<void> _addFromProducers() async {
-    var context = CorrectionProducerContext(
+    var context = CorrectionProducerContext.create(
       selectionOffset: selectionOffset,
       selectionLength: selectionLength,
       resolvedResult: resolvedResult,
       workspace: workspace,
     );
-
-    var setupSuccess = context.setupCompute();
-    if (!setupSuccess) {
-      return;
+    if (context == null) {
+      return assists;
     }
 
     Future<void> compute(CorrectionProducer producer) async {
diff --git a/pkg/analysis_server/lib/src/services/correction/base_processor.dart b/pkg/analysis_server/lib/src/services/correction/base_processor.dart
index 0750898..25b6c84 100644
--- a/pkg/analysis_server/lib/src/services/correction/base_processor.dart
+++ b/pkg/analysis_server/lib/src/services/correction/base_processor.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'package:analysis_server/src/services/correction/util.dart';
 import 'package:analysis_server/src/utilities/flutter.dart';
 import 'package:analyzer/dart/analysis/results.dart';
@@ -31,18 +29,18 @@
   final ResolvedUnitResult resolvedResult;
   final ChangeWorkspace workspace;
 
-  AstNode node;
+  AstNode? node;
 
   BaseProcessor({
     this.selectionOffset = -1,
     this.selectionLength = 0,
-    @required this.resolvedResult,
-    @required this.workspace,
-  })  : file = resolvedResult.path,
+    required this.resolvedResult,
+    required this.workspace,
+  })   : file = resolvedResult.path!,
         session = resolvedResult.session,
         sessionHelper = AnalysisSessionHelper(resolvedResult.session),
         typeProvider = resolvedResult.typeProvider,
-        selectionEnd = (selectionOffset ?? 0) + (selectionLength ?? 0),
+        selectionEnd = selectionOffset + selectionLength,
         utils = CorrectionUtils(resolvedResult);
 
   Flutter get flutter => Flutter.instance;
diff --git a/pkg/analysis_server/lib/src/services/correction/bulk_fix_processor.dart b/pkg/analysis_server/lib/src/services/correction/bulk_fix_processor.dart
index 093355b..9b3dba2 100644
--- a/pkg/analysis_server/lib/src/services/correction/bulk_fix_processor.dart
+++ b/pkg/analysis_server/lib/src/services/correction/bulk_fix_processor.dart
@@ -263,7 +263,7 @@
         (name) => [],
       );
 
-      var context = CorrectionProducerContext(
+      var context = CorrectionProducerContext.create(
         applyingBulkFixes: true,
         dartFixContext: fixContext,
         diagnostic: diagnostic,
@@ -272,6 +272,9 @@
         selectionLength: diagnostic.length,
         workspace: workspace,
       );
+      if (context == null) {
+        return;
+      }
 
       for (final multiGenerator in multiGenerators) {
         final multiProducer = multiGenerator();
@@ -314,7 +317,7 @@
       ResolvedUnitResult result,
       AnalysisError diagnostic,
       TransformOverrideSet overrideSet) async {
-    var context = CorrectionProducerContext(
+    var context = CorrectionProducerContext.create(
       applyingBulkFixes: true,
       dartFixContext: fixContext,
       diagnostic: diagnostic,
@@ -324,9 +327,7 @@
       selectionLength: diagnostic.length,
       workspace: workspace,
     );
-
-    var setupSuccess = context.setupCompute();
-    if (!setupSuccess) {
+    if (context == null) {
       return;
     }
 
diff --git a/pkg/analysis_server/lib/src/services/correction/dart/abstract_producer.dart b/pkg/analysis_server/lib/src/services/correction/dart/abstract_producer.dart
index 6bef12b..425dc82 100644
--- a/pkg/analysis_server/lib/src/services/correction/dart/abstract_producer.dart
+++ b/pkg/analysis_server/lib/src/services/correction/dart/abstract_producer.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'dart:math' as math;
 
 import 'package:_fe_analyzer_shared/src/scanner/token.dart';
@@ -31,7 +29,6 @@
 import 'package:analyzer_plugin/utilities/change_builder/change_workspace.dart';
 import 'package:analyzer_plugin/utilities/fixes/fixes.dart';
 import 'package:analyzer_plugin/utilities/range_factory.dart';
-import 'package:meta/meta.dart';
 
 /// An object that can compute a correction (fix or assist) in a Dart file.
 abstract class CorrectionProducer extends SingleCorrectionProducer {
@@ -56,28 +53,30 @@
   Future<void> compute(ChangeBuilder builder);
 
   /// Return the class, enum or mixin declaration for the given [element].
-  Future<ClassOrMixinDeclaration> getClassOrMixinDeclaration(
+  Future<ClassOrMixinDeclaration?> getClassOrMixinDeclaration(
       ClassElement element) async {
     var result = await sessionHelper.getElementDeclaration(element);
-    if (result.node is ClassOrMixinDeclaration) {
-      return result.node;
+    var node = result?.node;
+    if (node is ClassOrMixinDeclaration) {
+      return node;
     }
     return null;
   }
 
   /// Return the extension declaration for the given [element].
-  Future<ExtensionDeclaration> getExtensionDeclaration(
+  Future<ExtensionDeclaration?> getExtensionDeclaration(
       ExtensionElement element) async {
     var result = await sessionHelper.getElementDeclaration(element);
-    if (result.node is ExtensionDeclaration) {
-      return result.node;
+    var node = result?.node;
+    if (node is ExtensionDeclaration) {
+      return node;
     }
     return null;
   }
 
   /// Return the class element associated with the [target], or `null` if there
   /// is no such class element.
-  ClassElement getTargetClassElement(Expression target) {
+  ClassElement? getTargetClassElement(Expression target) {
     var type = target.staticType;
     if (type is InterfaceType) {
       return type.element;
@@ -92,7 +91,7 @@
 
   /// Returns an expected [DartType] of [expression], may be `null` if cannot be
   /// inferred.
-  DartType inferUndefinedExpressionType(Expression expression) {
+  DartType? inferUndefinedExpressionType(Expression expression) {
     var parent = expression.parent;
     // myFunction();
     if (parent is ExpressionStatement) {
@@ -120,9 +119,7 @@
       var assignment = parent;
       if (assignment.leftHandSide == expression) {
         var rhs = assignment.rightHandSide;
-        if (rhs != null) {
-          return rhs.staticType;
-        }
+        return rhs.staticType;
       }
     }
     // v = myFunction();
@@ -227,47 +224,72 @@
   final AnalysisSessionHelper sessionHelper;
   final ResolvedUnitResult resolvedResult;
   final ChangeWorkspace workspace;
-  final DartFixContext dartFixContext;
+
+  /// TODO(migration) Make it non-nullable, specialize "fix" context?
+  final DartFixContext? dartFixContext;
 
   /// A flag indicating whether the correction producers will be run in the
   /// context of applying bulk fixes.
   final bool applyingBulkFixes;
 
-  final Diagnostic diagnostic;
+  final Diagnostic? diagnostic;
 
-  final TransformOverrideSet overrideSet;
+  final TransformOverrideSet? overrideSet;
 
-  AstNode _node;
+  final AstNode node;
 
-  CorrectionProducerContext({
-    @required this.resolvedResult,
-    @required this.workspace,
+  CorrectionProducerContext._({
+    required this.resolvedResult,
+    required this.workspace,
     this.applyingBulkFixes = false,
     this.dartFixContext,
     this.diagnostic,
+    required this.node,
     this.overrideSet,
     this.selectionOffset = -1,
     this.selectionLength = 0,
-  })  : file = resolvedResult.path,
+  })  : file = resolvedResult.path!,
         session = resolvedResult.session,
         sessionHelper = AnalysisSessionHelper(resolvedResult.session),
         typeProvider = resolvedResult.typeProvider,
-        selectionEnd = (selectionOffset ?? 0) + (selectionLength ?? 0),
-        unit = resolvedResult.unit,
+        selectionEnd = selectionOffset + selectionLength,
+        unit = resolvedResult.unit!,
         utils = CorrectionUtils(resolvedResult);
 
-  AstNode get node => _node;
-
   /// Return `true` if the lint with the given [name] is enabled.
   bool isLintEnabled(String name) {
     var analysisOptions = session.analysisContext.analysisOptions;
     return analysisOptions.isLintEnabled(name);
   }
 
-  bool setupCompute() {
-    final locator = NodeLocator(selectionOffset, selectionEnd);
-    _node = locator.searchWithin(resolvedResult.unit);
-    return _node != null;
+  static CorrectionProducerContext? create({
+    required ResolvedUnitResult resolvedResult,
+    required ChangeWorkspace workspace,
+    bool applyingBulkFixes = false,
+    DartFixContext? dartFixContext,
+    Diagnostic? diagnostic,
+    TransformOverrideSet? overrideSet,
+    int selectionOffset = -1,
+    int selectionLength = 0,
+  }) {
+    var selectionEnd = selectionOffset + selectionLength;
+    var locator = NodeLocator(selectionOffset, selectionEnd);
+    var node = locator.searchWithin(resolvedResult.unit);
+    if (node == null) {
+      return null;
+    }
+
+    return CorrectionProducerContext._(
+      resolvedResult: resolvedResult,
+      workspace: workspace,
+      node: node,
+      applyingBulkFixes: applyingBulkFixes,
+      dartFixContext: dartFixContext,
+      diagnostic: diagnostic,
+      overrideSet: overrideSet,
+      selectionOffset: selectionOffset,
+      selectionLength: selectionLength,
+    );
   }
 }
 
@@ -283,53 +305,54 @@
   /// Return the arguments that should be used when composing the message for an
   /// assist, or `null` if the assist message has no parameters or if this
   /// producer doesn't support assists.
-  List<Object> get assistArguments => null;
+  List<Object>? get assistArguments => null;
 
   /// Return the assist kind that should be used to build an assist, or `null`
   /// if this producer doesn't support assists.
-  AssistKind get assistKind => null;
+  AssistKind? get assistKind => null;
 
   /// Return the length of the error message being fixed, or `null` if there is
   /// no diagnostic.
-  int get errorLength => diagnostic?.problemMessage?.length;
+  int? get errorLength => diagnostic?.problemMessage.length;
 
   /// Return the text of the error message being fixed, or `null` if there is
   /// no diagnostic.
-  String get errorMessage => diagnostic?.problemMessage?.message;
+  String? get errorMessage => diagnostic?.problemMessage.message;
 
   /// Return the offset of the error message being fixed, or `null` if there is
   /// no diagnostic.
-  int get errorOffset => diagnostic?.problemMessage?.offset;
+  int? get errorOffset => diagnostic?.problemMessage.offset;
 
   /// Return the arguments that should be used when composing the message for a
   /// fix, or `null` if the fix message has no parameters or if this producer
   /// doesn't support fixes.
-  List<Object> get fixArguments => null;
+  List<Object>? get fixArguments => null;
 
   /// Return the fix kind that should be used to build a fix, or `null` if this
   /// producer doesn't support fixes.
-  FixKind get fixKind => null;
+  FixKind? get fixKind => null;
 
   /// Return the arguments that should be used when composing the message for a
   /// multi-fix, or `null` if the fix message has no parameters or if this
   /// producer doesn't support multi-fixes.
-  List<Object> get multiFixArguments => null;
+  List<Object>? get multiFixArguments => null;
 
   /// Return the fix kind that should be used to build a multi-fix, or `null` if
   /// this producer doesn't support multi-fixes.
-  FixKind get multiFixKind => null;
+  FixKind? get multiFixKind => null;
 }
 
 /// The behavior shared by [CorrectionProducer] and [MultiCorrectionProducer].
 abstract class _AbstractCorrectionProducer {
   /// The context used to produce corrections.
-  CorrectionProducerContext _context;
+  /// TODO(migration) Make it not `late`, require in constructor.
+  late CorrectionProducerContext _context;
 
   /// The most deeply nested node that completely covers the highlight region of
   /// the diagnostic, or `null` if there is no diagnostic, such a node does not
   /// exist, or if it hasn't been computed yet. Use [coveredNode] to access this
   /// field.
-  AstNode _coveredNode;
+  AstNode? _coveredNode;
 
   /// Initialize a newly created producer.
   _AbstractCorrectionProducer();
@@ -340,7 +363,7 @@
   /// The most deeply nested node that completely covers the highlight region of
   /// the diagnostic, or `null` if there is no diagnostic or if such a node does
   /// not exist.
-  AstNode get coveredNode {
+  AstNode? get coveredNode {
     // TODO(brianwilkerson) Consider renaming this to `coveringNode`.
     if (_coveredNode == null) {
       var diagnostic = this.diagnostic;
@@ -358,7 +381,7 @@
 
   /// Return the diagnostic being fixed, or `null` if this producer is being
   /// used to produce an assist.
-  Diagnostic get diagnostic => _context.diagnostic;
+  Diagnostic? get diagnostic => _context.diagnostic;
 
   /// Returns the EOL to use for this [CompilationUnit].
   String get eol => utils.endOfLine;
@@ -375,7 +398,7 @@
 
   /// Return the set of overrides to be applied to the transform set when
   /// running tests, or `null` if there are no overrides to apply.
-  TransformOverrideSet get overrideSet => _context.overrideSet;
+  TransformOverrideSet? get overrideSet => _context.overrideSet;
 
   ResolvedUnitResult get resolvedResult => _context.resolvedResult;
 
@@ -413,7 +436,7 @@
 
   /// Return the function body of the most deeply nested method or function that
   /// encloses the [node], or `null` if the node is not in a method or function.
-  FunctionBody getEnclosingFunctionBody() {
+  FunctionBody? getEnclosingFunctionBody() {
     var closure = node.thisOrAncestorOfType<FunctionExpression>();
     if (closure != null) {
       return closure.body;
@@ -441,7 +464,7 @@
   /// Return the top-level declarations with the [name] in libraries that are
   /// available to this context.
   List<TopLevelDeclaration> getTopLevelDeclarations(String name) =>
-      _context.dartFixContext.getTopLevelDeclarations(name);
+      _context.dartFixContext!.getTopLevelDeclarations(name);
 
   /// Return `true` the lint with the given [name] is enabled.
   bool isLintEnabled(String name) {
diff --git a/pkg/analysis_server/lib/src/services/correction/dart/add_async.dart b/pkg/analysis_server/lib/src/services/correction/dart/add_async.dart
index 79c8f63..289a537 100644
--- a/pkg/analysis_server/lib/src/services/correction/dart/add_async.dart
+++ b/pkg/analysis_server/lib/src/services/correction/dart/add_async.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'package:analysis_server/src/services/correction/dart/abstract_producer.dart';
 import 'package:analysis_server/src/services/correction/fix.dart';
 import 'package:analyzer/dart/ast/ast.dart';
@@ -27,21 +25,22 @@
   Future<void> compute(ChangeBuilder builder) async {
     if (isForMissingReturn) {
       var parent = node.parent;
-      DartType returnType;
-      FunctionBody body;
+      FunctionBody? body;
+      DartType? returnType;
       if (parent is FunctionDeclaration) {
-        returnType = parent.declaredElement.returnType;
         body = parent.functionExpression.body;
+        returnType = parent.declaredElement!.returnType;
       } else if (parent is MethodDeclaration) {
-        returnType = parent.declaredElement.returnType;
         body = parent.body;
+        returnType = parent.declaredElement!.returnType;
       }
-      if (body == null) {
+      if (body == null || returnType == null) {
         return;
       }
       if (_isFutureVoid(returnType) && _hasNoReturns(body)) {
+        var final_body = body;
         await builder.addDartFileEdit(file, (builder) {
-          builder.addSimpleInsertion(body.offset, 'async ');
+          builder.addSimpleInsertion(final_body.offset, 'async ');
         });
       }
     } else {
diff --git a/pkg/analysis_server/lib/src/services/correction/dart/wrap_in_future.dart b/pkg/analysis_server/lib/src/services/correction/dart/wrap_in_future.dart
index 794bb72..c1892ff 100644
--- a/pkg/analysis_server/lib/src/services/correction/dart/wrap_in_future.dart
+++ b/pkg/analysis_server/lib/src/services/correction/dart/wrap_in_future.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'package:analysis_server/src/services/correction/dart/abstract_producer.dart';
 import 'package:analysis_server/src/services/correction/fix.dart';
 import 'package:analyzer/dart/ast/ast.dart';
@@ -20,21 +18,26 @@
     //
     // Extract the information needed to build the edit.
     //
-    Expression expression;
+    Expression? expression;
+    var node = this.node;
     if (node is ReturnStatement) {
-      expression = (node as ReturnStatement).expression;
+      expression = node.expression;
     } else if (node is Expression) {
       expression = node;
-    } else {
+    }
+    if (expression == null) {
       return;
     }
     var value = utils.getNodeText(expression);
     //
     // Build the edit.
     //
+    var final_expression = expression;
     await builder.addDartFileEdit(file, (builder) {
       builder.addSimpleReplacement(
-          range.node(expression), 'Future.value($value)');
+        range.node(final_expression),
+        'Future.value($value)',
+      );
     });
   }
 
diff --git a/pkg/analysis_server/lib/src/services/correction/fix_internal.dart b/pkg/analysis_server/lib/src/services/correction/fix_internal.dart
index dfc9b79..e8795a1f 100644
--- a/pkg/analysis_server/lib/src/services/correction/fix_internal.dart
+++ b/pkg/analysis_server/lib/src/services/correction/fix_internal.dart
@@ -210,16 +210,19 @@
     var workspace = context.workspace;
     var resolveResult = context.resolveResult;
 
-    var generators = _getGenerators(
-        error.errorCode,
-        CorrectionProducerContext(
-          dartFixContext: context,
-          diagnostic: error,
-          resolvedResult: resolveResult,
-          selectionOffset: context.error.offset,
-          selectionLength: context.error.length,
-          workspace: workspace,
-        ));
+    var correctionContext = CorrectionProducerContext.create(
+      dartFixContext: context,
+      diagnostic: error,
+      resolvedResult: resolveResult,
+      selectionOffset: context.error.offset,
+      selectionLength: context.error.length,
+      workspace: workspace,
+    );
+    if (correctionContext == null) {
+      return const <Fix>[];
+    }
+
+    var generators = _getGenerators(error.errorCode, correctionContext);
 
     var fixes = <Fix>[];
     for (var generator in generators) {
@@ -248,7 +251,7 @@
 
   Future<void> _fixError(DartFixContext fixContext, FixState fixState,
       CorrectionProducer producer, AnalysisError diagnostic) async {
-    var context = CorrectionProducerContext(
+    var context = CorrectionProducerContext.create(
       applyingBulkFixes: true,
       dartFixContext: fixContext,
       diagnostic: diagnostic,
@@ -257,9 +260,7 @@
       selectionLength: diagnostic.length,
       workspace: fixContext.workspace,
     );
-
-    var setupSuccess = context.setupCompute();
-    if (!setupSuccess) {
+    if (context == null) {
       return;
     }
 
@@ -1745,7 +1746,7 @@
 
   Future<void> _addFromProducers() async {
     var error = fixContext.error;
-    var context = CorrectionProducerContext(
+    var context = CorrectionProducerContext.create(
       dartFixContext: fixContext,
       diagnostic: error,
       resolvedResult: resolvedResult,
@@ -1753,9 +1754,7 @@
       selectionLength: fixContext.error.length,
       workspace: workspace,
     );
-
-    var setupSuccess = context.setupCompute();
-    if (!setupSuccess) {
+    if (context == null) {
       return;
     }