Change analysis server protocol to omit empty lists when optional.

pkg/analysis_server/lib/src/services/correction/change.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // 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.
 
 library services.correction.change;
 
 import 'package:analysis_server/src/constants.dart';
 import 'package:analysis_server/src/protocol2.dart';
 import 'package:analysis_server/src/services/json.dart';
 
@@ skipping 23 matching lines @@
   Position selection;
 
   Change(this.message);
 
   /**
    * Adds [edit] to the [FileEdit] for the given [file].
    */
   void addEdit(String file, SourceEdit edit) {
     SourceFileEdit fileEdit = getFileEdit(file);
     if (fileEdit == null) {
-      fileEdit = new SourceFileEdit(file, <SourceEdit>[]);
+      fileEdit = new SourceFileEdit(file);
       addFileEdit(fileEdit);
     }
     fileEdit.add(edit);
   }
 
   /**
    * Adds the given [FileEdit].
    */
   void addFileEdit(SourceFileEdit edit) {
     fileEdits.add(edit);
@@ skipping 110 matching lines @@
   static const PARAMETER = const LinkedEditSuggestionKind('PARAMETER');
   static const TYPE = const LinkedEditSuggestionKind('TYPE');
   static const VARIABLE = const LinkedEditSuggestionKind('VARIABLE');
   final String name;
 
   const LinkedEditSuggestionKind(this.name);
 
   @override
   String toString() => name;
 }