WP_REST_Menu_Items_Controller::get_collection_params()

	public function get_collection_params() {
		$query_params = parent::get_collection_params();

		$query_params['menu_order'] = array(
			'description' => __( 'Limit result set to posts with a specific menu_order value.' ),
			'type'        => 'integer',
		);

		$query_params['order'] = array(
			'description' => __( 'Order sort attribute ascending or descending.' ),
			'type'        => 'string',
			'default'     => 'asc',
			'enum'        => array( 'asc', 'desc' ),
		);

		$query_params['orderby'] = array(
			'description' => __( 'Sort collection by object attribute.' ),
			'type'        => 'string',
			'default'     => 'menu_order',
			'enum'        => array(
				'author',
				'date',
				'id',
				'include',
				'modified',
				'parent',
				'relevance',
				'slug',
				'include_slugs',
				'title',
				'menu_order',
			),
		);
		// Change default to 100 items.
		$query_params['per_page']['default'] = 100;

		return $query_params;
	}