WP_Nav_Menu_Widget::widget

	public function widget( $args, $instance ) {
		// Get menu.
		$nav_menu = ! empty( $instance['nav_menu'] ) ? wp_get_nav_menu_object( $instance['nav_menu'] ) : false;

		if ( ! $nav_menu ) {
			return;
		}

		$default_title = __( 'Menu' );
		$title         = ! empty( $instance['title'] ) ? $instance['title'] : '';

		/** This filter is documented in wp-includes/widgets/class-wp-widget-pages.php */
		$title = apply_filters( 'widget_title', $title, $instance, $this->id_base );

		echo $args['before_widget'];

		if ( $title ) {
			echo $args['before_title'] . $title . $args['after_title'];
		}

		$format = current_theme_supports( 'html5', 'navigation-widgets' ) ? 'html5' : 'xhtml';

		/**
		 * Filters the HTML format of widgets with navigation links.
		 *
		 * @since 5.5.0
		 *
		 * @param string $format The type of markup to use in widgets with navigation links.
		 *                       Accepts 'html5', 'xhtml'.
		 */
		$format = apply_filters( 'navigation_widgets_format', $format );

		if ( 'html5' === $format ) {
			// The title may be filtered: Strip out HTML and make sure the aria-label is never empty.
			$title      = trim( strip_tags( $title ) );
			$aria_label = $title ? $title : $default_title;

			$nav_menu_args = array(
				'fallback_cb'          => '',
				'menu'                 => $nav_menu,
				'container'            => 'nav',
				'container_aria_label' => $aria_label,
				'items_wrap'           => '<ul id="%1$s" class="%2$s">%3$s</ul>',
			);