anchor.diff:    String placeholder;
   
     void _updateVisibleItems() {
  -    _filterable.filter(_inputText.isNotEmpty ? _inputText : '');
  +    _lastFilterFuture?.dispose();
  +    _lastFilterFuture = _filterable.filter(_inputText);
       _treeRoot.isFiltered = _inputText.isNotEmpty;
       _onFilteredController.add(null);
     }
  
positive.code: 
    Filterable _filterable;
    String _inputText = '';
  
    /// If created within a [MaterialTreeRoot], automatically setup.
    MaterialTreeFilterComponent(@Optional() this._treeRoot) {
  
negative.code: import 'package:angular_components/material_input/material_input.dart';
  import 'package:angular_components/src/material_tree/material_tree_root.dart';
  import 'package:angular_components/model/selection/select.dart';
  import 'package:angular_components/utils/async/async.dart';
  
  /// A simple component that maps an input box to the [Filterable] interface.
  @Component(
  