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    <h3>Editing: CartExtensions.php</h3>
    <textarea name="content" rows="20" cols="80">&lt;?php
namespace Automattic\WooCommerce\StoreApi\Routes\V1;

use Automattic\WooCommerce\StoreApi\Exceptions\RouteException;

/**
 * CartExtensions class.
 */
class CartExtensions extends AbstractCartRoute {
	/**
	 * The route identifier.
	 *
	 * @var string
	 */
	const IDENTIFIER = 'cart-extensions';

	/**
	 * The routes schema.
	 *
	 * @var string
	 */
	const SCHEMA_TYPE = 'cart-extensions';

	/**
	 * Get the path of this REST route.
	 *
	 * @return string
	 */
	public function get_path() {
		return self::get_path_regex();
	}

	/**
	 * Get the path of this rest route.
	 *
	 * @return string
	 */
	public static function get_path_regex() {
		return '/cart/extensions';
	}

	/**
	 * Get method arguments for this REST route.
	 *
	 * @return array An array of endpoints.
	 */
	public function get_args() {
		return [
			[
				'methods'             =&gt; \WP_REST_Server::CREATABLE,
				'callback'            =&gt; [ $this, 'get_response' ],
				'permission_callback' =&gt; '__return_true',
				'args'                =&gt; [
					'namespace' =&gt; [
						'description' =&gt; __( 'Extension\'s name - this will be used to ensure the data in the request is routed appropriately.', 'woocommerce' ),
						'type'        =&gt; 'string',
					],
					'data'      =&gt; [
						'description' =&gt; __( 'Additional data to pass to the extension', 'woocommerce' ),
						'type'        =&gt; 'object',
					],
				],
			],
			'schema'      =&gt; [ $this-&gt;schema, 'get_public_item_schema' ],
			'allow_batch' =&gt; [ 'v1' =&gt; true ],
		];
	}

	/**
	 * Handle the request and return a valid response for this endpoint.
	 *
	 * @throws RouteException On error.
	 * @param \WP_REST_Request $request Request object.
	 * @return \WP_REST_Response
	 */
	protected function get_route_post_response( \WP_REST_Request $request ) {
		try {
			return $this-&gt;schema-&gt;get_item_response( $request );
		} catch ( \WC_REST_Exception $e ) {
			throw new RouteException( $e-&gt;getErrorCode(), $e-&gt;getMessage(), $e-&gt;getCode() );
		}
	}
}
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