anchor.diff:    /// Read the file content and ensure that all of the file properties are
     /// consistent with the read content, including API signature.
     ///
  -  /// If [allowCached] is `true`, don't read the content of the file if it
  -  /// is already cached (in another [FileSystemState], because otherwise we
  -  /// would not create this new instance of [FileState] and refresh it).
  -  ///
     /// Return `true` if the API signature changed since the last refresh.
  -  bool refresh({bool allowCached = false}) {
  +  bool refresh() {
       counterFileStateRefresh++;
   
       var timerWasRunning = timerFileStateRefresh.isRunning;
  
positive.code:     }
  
      _invalidateCurrentUnresolvedData();
  
      if (!allowCached) {
        _fsState.markFileForReading(path);
      }
  
      {
        var rawFileState = _fsState._fileContentCache.get(path);
  
negative.code:           packageLanguageVersion);
        _uriToFile[uri] = file;
        _addFileWithPath(path, file);
        file.refresh();
      }
      return Either2.t1(file);
    }
  