rest-api.php

<?php
/**
 * PHP and WordPress configuration compatibility functions for the Gutenberg
 * editor plugin changes related to REST API.
 *
 * @package gutenberg
 */

if ( ! defined( 'ABSPATH' ) ) {
	die( 'Silence is golden.' );
}

/**
 * Overrides the REST controller for the `wp_global_styles` post type.
 *
 * @param array $args Array of arguments for registering a post type.
 *                          See the register_post_type() function for accepted arguments.
 *
 * @return array Array of arguments for registering a post type.
 */
function gutenberg_override_global_styles_endpoint( array $args ): array {
	$args['rest_controller_class']   = 'WP_REST_Global_Styles_Controller_Gutenberg';
	$args['late_route_registration'] = true;
	$args['show_in_rest']            = true;
	$args['rest_base']               = 'global-styles';

	return $args;
}
add_filter( 'register_wp_global_styles_post_type_args', 'gutenberg_override_global_styles_endpoint', 10, 2 );

/**
 * Registers the Edit Site Export REST API routes.
 */
function gutenberg_register_edit_site_export_controller_endpoints() {
	$edit_site_export_controller = new WP_REST_Edit_Site_Export_Controller_Gutenberg();
	$edit_site_export_controller->register_routes();
}
add_action( 'rest_api_init', 'gutenberg_register_edit_site_export_controller_endpoints' );