protected function addDropdown(ItemInterface $menu, $label, $caret = true)
    {
        $item = $this->addLinkURI($menu, $label, '#');
        $item->setChildrenAttributes(array('class' => 'treeview-menu'));
        $item->setAttributes(array('class' => 'treeview'));
        $item->setExtra('caret', $caret);

        return $item;
    }