Use HasToJson when set Reponse/Notification parameters.

pkg/analysis_server/lib/src/search/search_result.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 search.search_result;
 
+import 'package:analysis_server/src/collections.dart';
 import 'package:analysis_server/src/computer/element.dart';
 import 'package:analysis_server/src/constants.dart';
 import 'package:analysis_services/search/search_engine.dart';
 import 'package:analyzer/src/generated/element.dart' as engine;
 
 
 /**
  * A single result from a search request.
  */
-class SearchResult {
+class SearchResult implements HasToJson {
   /**
    * The kind of element that was found or the kind of reference that was found.
    */
   final SearchResultKind kind;
 
   /**
    * Is `true` if the result is a potential match but cannot be confirmed to be
    * a match.
    *
    * For example, if all references to a method `m` defined in some class were
@@ skipping 120 matching lines @@
     }
     if (name == REFERENCE.name) {
       return REFERENCE;
     }
     return UNKNOWN;
   }
 
   @override
   String toString() => name;
 }