anchor.diff:    }
     
     isDirty() {
  -    return !_dirtiFields.isEmpty();
  +    return !_dirtyFields.isEmpty();
     }
     
     
  
positive.code:   void setDirty(String fieldName){
      super.setDirty(fieldName);
      if (_parent !== null) {
        _parent.setDirty(_pathToMe);
      }
    }
    remove() {
  
negative.code:   }  
    
    void setDirty(String fieldName) {
      if (_dirtyFields === null){
        return;
      }
      _dirtyFields.add(fieldName);
    }
    
    void clearDirtyStatus() {
      _dirtyFields.clear();
    }
    
    void onValueChanging(String fieldName, newValue) {
  