protected function renderNavbarMenu(AbstractContainer $container, array $options)
    {
        // Create iterator
        $iterator = new \RecursiveIteratorIterator($container, \RecursiveIteratorIterator::SELF_FIRST);
        $iterator->setMaxDepth(self::MAX_RENDER_DEPTH);

        // Add pages
        $html      = '';
        $prevDepth = -1;
        foreach ($iterator as $page) {
            if (!$this->accept($page)) {
                continue;
            }
            // Create navbar page
            $depth = $iterator->getDepth();
            $html .= $this->renderNavbarMenuPage($page, $options, $depth, $prevDepth);

            // Store depth for next iteration
            $prevDepth = $depth;
        }

        // Check if any html was created
        if ($html) {
            // Close open ul/li tags
            for ($i = $prevDepth + 1; $i > 0; $i--) {
                $html .= '</li></ul>';
            }
        }

        return $html;
    }