add preserverHeaderCase argument (#8)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 67c7d12..840953a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,11 @@
+## v0.2.0
+
+* Preparation for [HttpHeaders change]. Update signature of `add()`
+  and `set()` to match new signature of `HttpHeaders`. The
+  parameter is not yet forwarded and will not behave as expected.
+
+  [HttpHeaders change]: https://github.com/dart-lang/sdk/issues/39657
+
 ## v0.1.4
 
 * Fixed issue where query parameters were not being sent as part of requests.
diff --git a/lib/src/sync_http.dart b/lib/src/sync_http.dart
index fbc0f10..77464a8 100644
--- a/lib/src/sync_http.dart
+++ b/lib/src/sync_http.dart
@@ -149,7 +149,7 @@
 
   /// Add [value] to the list of values associated with header [name].
   @override
-  void add(String name, Object value) {
+  void add(String name, Object value, {bool preserveHeaderCase = false}) {
     switch (name) {
       case HttpHeaders.acceptCharsetHeader:
       case HttpHeaders.acceptEncodingHeader:
@@ -222,9 +222,9 @@
 
   /// Replace values associated with key [name] with [value].
   @override
-  void set(String name, Object value) {
+  void set(String name, Object value, {bool preserveHeaderCase = false}) {
     removeAll(name);
-    add(name, value);
+    add(name, value, preserveHeaderCase: preserveHeaderCase);
   }
 
   /// Returns the values associated with key [name], if it exists, otherwise
@@ -449,7 +449,7 @@
   List<String> operator [](String name) => _headers[name];
 
   @override
-  void add(String name, Object value) {
+  void add(String name, Object value, {bool preserveHeaderCase = false}) {
     throw new UnsupportedError('Response headers are immutable');
   }
 
@@ -586,7 +586,7 @@
   }
 
   @override
-  void set(String name, Object value) {
+  void set(String name, Object value, {bool preserveHeaderCase = false}) {
     throw new UnsupportedError('Response headers are immutable');
   }
 
diff --git a/pubspec.yaml b/pubspec.yaml
index a590f77..eca05dd 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,6 @@
 name: sync_http
-version: 0.1.4
+version: 0.2.0
+publish_to: none
 author: Dart Team <misc@dartlang.org>
 description: Synchronous HTTP client for Dart.
 homepage: https://github.com/dart-lang/sync_http