anchor.diff:    final List<String> _candidates;
   
     /// The time of last modification of the file under [_validPath].
  -  int? _lastModified;
  +  _TimestampAndLength? _lastModified;
   
     /// The resource provider used for polling the files.
     final ResourceProvider _provider;
  
positive.code: 
    _PerWorkspaceData(this.trigger, this.pollSubscription);
  }
  
negative.code:     } else if (_lastModified != null && modified != _lastModified) {
        result = WatchEvent(ChangeType.MODIFY, _validPath!);
      }
  
      _lastModified = modified;
      return result;
    }
  