anchor.diff:  
     List<T> _rawList;
   
  -  ImmutableList<T> _currentList;
  +  late ImmutableList<T> _currentList;
   
     @override
     List<T> get value => _currentList;
   
     @override
  +  // This override is needed to change visibility of the method.
  +  // ignore: unnecessary_overrides
     void notifyListeners() {
       super.notifyListeners();
     }
  
positive.code:     _activeTimer = Timer(
          Duration(
              milliseconds:
                  currentTime - _lastRequestTime + delayBetweenRequests), () {
        _activeTimer = null;
        requestScheduledButNotStarted = false;
        _performRequest();
  
negative.code: 
      final currentTime = DateTime.now().millisecondsSinceEpoch;
      if (_lastRequestTime == null ||
          _lastRequestTime! + delayBetweenRequests <= currentTime) {
        // Safe to perform the request immediately.
        _performRequest();
        return;
  