woocommerce/includes/api/wc-rest-order-refunds-controller.php

<?php
/**
 * REST API Order Refunds controller
 *
 * Handles requests to the /orders/<order_id>/refunds endpoint.
 *
 * @author   WooThemes
 * @category API
 * @package  WooCommerce/API
 * @since    2.6.0
 */

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * REST API Order Refunds controller class.
 *
 * @package WooCommerce/API
 * @extends WC_REST_Posts_Controller
 */
class WC_REST_Order_Refunds_Controller extends WC_REST_Posts_Controller {

	/**
	 * Endpoint namespace.
	 *
	 * @var string
	 */
	public $namespace = 'wc/v1';

	/**
	 * Route base.
	 *
	 * @var string
	 */
	protected $rest_base = 'orders/(?P<order_id>[\d]+)/refunds';

	/**
	 * Post type.
	 *
	 * @var string
	 */
	protected $post_type = 'shop_order_refund';

	/**
	 * Register the routes for order refunds.
	 */
	public function register_routes() {
		register_rest_route( $this->namespace, '/' . $this->rest_base . '/(?P<id>[\d]+)', array(
			array(
				'methods'             => WP_REST_Server::DELETABLE,
				'callback'            => array( $this, 'delete_item' ),
				'permission_callback' => array( $this, 'delete_item_permissions_check' ),
				'args'                => array(
					'force' => array(
						'default'     => false,
						'description' => __( 'Whether to bypass trash and force deletion.', 'woocommerce' ),
					),
				),
			),
		) );
	}
}