yii2 navbar with dropdown

echo Nav::widget([    'items' => [        [            'label' => 'Home',            'url' => ['site/index'],            'linkOptions' => [...],        ],        [            'label' => 'Dropdown',            'items' => [                 ['label' => 'Level 1 - Dropdown A', 'url' => '#'],                 '<li class="divider"></li>',                 '<li class="dropdown-header">Dropdown Header</li>',                 ['label' => 'Level 1 - Dropdown B', 'url' => '#'],            ],        ],    ],    'options' => ['class' =>'navbar-nav'],]);