### Question:
CheckTreeView extends TreeView<T> { public final CheckModel<TreeItem<T>> getCheckModel() { return checkModel == null ? null : checkModel.get(); } CheckTreeView();  CheckTreeView(final CheckBoxTreeItem<T> root); BooleanProperty getItemBooleanProperty(int index); final void setCheckModel(CheckModel<TreeItem<T>> value); final CheckModel<TreeItem<T>> getCheckModel(); final ObjectProperty<CheckModel<TreeItem<T>>> checkModelProperty();  }### Answer:
@Test public void testConcurrentModification() { checkTreeView.getCheckModel().checkAll(); checkTreeView.getCheckModel().clearChecks(); }