Change analysis server protocol to omit empty lists when optional.

pkg/analysis_server/lib/src/edit/edit_domain.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 edit.domain;
 
 import 'package:analysis_server/src/analysis_server.dart';
 import 'package:analysis_server/src/constants.dart';
 import 'package:analysis_server/src/edit/fix.dart';
 import 'package:analysis_server/src/protocol.dart';
@@ skipping 72 matching lines @@
       if (elements.isNotEmpty) {
         Element element = elements[0];
         RenameRefactoring renameRefactoring =
             new RenameRefactoring(searchEngine, element);
         if (renameRefactoring != null) {
           kinds.add(RefactoringKind.RENAME);
         }
       }
     }
     // respond
-    return new EditGetAvailableRefactoringsResult(kinds).toResponse(request.id);
+    return new EditGetAvailableRefactoringsResult(kinds: kinds).toResponse(
+        request.id);
   }
 
   Response getFixes(Request request) {
     var params = new EditGetFixesParams.fromRequest(request);
     String file = params.file;
     int offset = params.offset;
     // add fixes
     List<ErrorFixes> errorFixesList = <ErrorFixes>[];
     List<CompilationUnit> units = server.getResolvedCompilationUnits(file);
     for (CompilationUnit unit in units) {
@@ skipping 32 matching lines @@
         return getAssists(request);
       } else if (requestName == EDIT_GET_FIXES) {
         return getFixes(request);
       }
     } on RequestFailure catch (exception) {
       return exception.response;
     }
     return null;
   }
 }