@Test
public void addItemsWithNullClickListener_doesNotThrow() {

    GridContextMenu<Object> gridContextMenu = new GridContextMenu<>();
    GridMenuItem<Object> foo = gridContextMenu.addItem("foo", null);
    gridContextMenu.addItem(new NativeButton(), null);
    foo.getSubMenu().addItem("bar", null);
    foo.getSubMenu().addItem(new NativeButton(), null);
}