anchor.diff:    final AnalysisServer server;
   
     /**
  -   * The [SearchEngine] for this server.
  -   */
  -  SearchEngine searchEngine;
  -
  -  /**
      * The next completion response id.
      */
     int _nextCompletionId = 0;
  -
  -  /**
  -   * The completion manager for most recent [Source] and [AnalysisContext],
  -   * or `null` if none.
  -   */
  -  CompletionManager _manager;
  -
  -  /**
  -   * The subscription for the cached context's source change stream.
  -   */
  -  StreamSubscription<SourcesChangedEvent> _sourcesChangedSubscription;
   
     /**
      * Code completion performance for the last completion operation.
  
positive.code:             completionId, replacementOffset, replacementLength, results, true)
          .toNotification());
    }
  
    /**
     * Discard the cache if a source other than the source referenced by
     * the cache changes or if any source is added, removed, or deleted.
     */
    void sourcesChanged(SourcesChangedEvent event) {
      bool shouldDiscardManager(SourcesChangedEvent event) {
        if (_manager == null) {
          return false;
        }
        if (event.wereSourcesAdded || event.wereSourcesRemovedOrDeleted) {
          return true;
        }
        var changedSources = event.changedSources;
        return changedSources.length > 2 ||
            (changedSources.length == 1 &&
                !changedSources.contains(_manager.source));
      }
  
      if (shouldDiscardManager(event)) {
        _discardManager();
      }
    }
  
    /**
     * Discard the sourcesChanged subscription if any
     */
    void _discardManager() {
      if (_sourcesChangedSubscription != null) {
        _sourcesChangedSubscription.cancel();
        _sourcesChangedSubscription = null;
      }
      if (_manager != null) {
        _manager.dispose();
        _manager = null;
      }
    }
  }
  
negative.code: import 'package:analysis_server/plugin/protocol/protocol.dart';
  import 'package:analysis_server/src/analysis_server.dart';
  import 'package:analysis_server/src/constants.dart';
  import 'package:analysis_server/src/provisional/completion/completion_core.dart'
      show CompletionRequest, CompletionResult;
  import 'package:analysis_server/src/services/completion/completion_core.dart';
  import 'package:analysis_server/src/services/completion/completion_manager.dart';
  import 'package:analyzer/src/generated/engine.dart';
  import 'package:analyzer/src/generated/source.dart';
  
  