Generate constants in server as we do in plugin

pkg/analysis_server/test/analysis/notification_occurrences_test.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.
 
 import 'dart:async';
 
 import 'package:analysis_server/protocol/protocol.dart';
+import 'package:analysis_server/protocol/protocol_constants.dart';
 import 'package:analysis_server/protocol/protocol_generated.dart';
-import 'package:analysis_server/src/constants.dart';
 import 'package:analyzer_plugin/protocol/protocol_common.dart';
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import '../analysis_abstract.dart';
 
 main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AnalysisNotificationOccurrencesTest);
   });
@@ skipping 56 matching lines @@
           '${occurrencesList.join('\n')}');
     }
   }
 
   Future prepareOccurrences() {
     addAnalysisSubscription(AnalysisService.OCCURRENCES, testFile);
     return _resultsAvailable.future;
   }
 
   void processNotification(Notification notification) {
-    if (notification.event == ANALYSIS_OCCURRENCES) {
+    if (notification.event == ANALYSIS_NOTIFICATION_OCCURRENCES) {
       var params = new AnalysisOccurrencesParams.fromNotification(notification);
       if (params.file == testFile) {
         occurrencesList = params.occurrences;
         _resultsAvailable.complete(null);
       }
     }
   }
 
   @override
   void setUp() {
@@ skipping 151 matching lines @@
   test_type_void() async {
     addTestFile('''
 void main() {
 }
 ''');
     await prepareOccurrences();
     int offset = findOffset('void main()');
     findRegion(offset, 'void'.length, false);
   }
 }