anchor.diff:  
     bool deselectOnRemove;
   
  -  CountGetter _totalEntitiesCount = _noCountGetter;
  +  CountGetter _totalEntitiesCount = () => -1;
   
     @override
     CountGetter get totalEntitiesCount => _totalEntitiesCount;
  
positive.code: 
    @override
    bool get isPageSelected =>
        supportsSelectAll &&
        selectedCount > 0 &&
        selectedCount == entitiesOnPageCount();
  
    @override
    void onRemove(T entity) {
  
negative.code: 
    bool _allSelected = false;
  
    CountGetter _totalEntitiesCount = () => -1;
  
    @override
    CountGetter get totalEntitiesCount => _totalEntitiesCount;
  
    @override
    set totalEntitiesCount(CountGetter value) {
  