apply_filters( 'nav_menu_css_class', string[] $classes, WP_Post $menu_item, stdClass $args, int $depth )

188		 *189		 * @param string[] $classes   Array of the CSS classes that are applied to the menu item's `<li>` element.190		 * @param WP_Post  $menu_item The current menu item object.191		 * @param stdClass $args      An object of wp_nav_menu() arguments.192		 * @param int      $depth     Depth of menu item. Used for padding.193		 */194		$class_names = implode( ' ', apply_filters( 'nav_menu_css_class', array_filter( $classes ), $menu_item, $args, $depth ) );195 196		/**197		 * Filters the ID attribute applied to a menu item's list item element.198		 *199		 * @since 3.0.1200		 * @since 4.1.0 The `$depth` parameter was added.