Unify the server and plugin versions of the generators

pkg/analysis_server/lib/src/plugin/notification_manager.dart

 // Copyright (c) 2017, 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:collection';
 
-import 'package:analysis_server/plugin/protocol/protocol.dart' as server;
+import 'package:analysis_server/protocol/protocol_generated.dart' as server;
 import 'package:analysis_server/src/channel/channel.dart';
 import 'package:analysis_server/src/plugin/result_collector.dart';
 import 'package:analysis_server/src/plugin/result_converter.dart';
 import 'package:analysis_server/src/plugin/result_merger.dart';
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer_plugin/protocol/protocol.dart' as plugin;
 import 'package:analyzer_plugin/protocol/protocol_constants.dart' as plugin;
 import 'package:analyzer_plugin/protocol/protocol_generated.dart' as plugin;
 
 /**
@@ skipping 371 matching lines @@
         }
       }
       return false;
     }
 
     // TODO(brianwilkerson) Return false if error notifications are globally
     // disabled.
     return isIncluded() && !isExcluded();
   }
 }