code: public void init(
        PreferencesFxModel model,
        StringProperty searchText,
        ObjectProperty<TreeItemPredicate<Category>> predicateProperty
    ) {
      this.model = model;
      initializeSearch();
      initializeSearchText(searchText);
      bindFilterPredicate(predicateProperty);
    }
docs: Initializes the SearchHandler by initially creating all necessary lists
  for filtering and setting up the bindings.
  
  @param searchText        textProperty of a TextField where the search string is being input
  @param predicateProperty of the rootItem of a {@link FilterableTreeItem}
  @apiNote Must be called to make the filtering work.