public function fail_order_args() {
		return [
			'order_id'      => [
				'description'       => __( 'Order ID in PayPal', 'event-tickets' ),
				'required'          => true,
				'type'              => 'string',
				'validate_callback' => static function ( $value ) {
					if ( ! is_string( $value ) ) {
						return new WP_Error( 'rest_invalid_param', 'The order ID argument must be a string.', [ 'status' => 400 ] );
					}

					return $value;
				},
				'sanitize_callback' => [ $this, 'sanitize_callback' ],
			],
			'failed_status' => [
				'description'       => __( 'To which status the failing should change this order to', 'event-tickets' ),
				'required'          => false,
				'type'              => 'string',
				'validate_callback' => static function ( $value ) {
					if ( ! is_string( $value ) ) {
						return new WP_Error( 'rest_invalid_param', 'The failed status argument must be a string.', [ 'status' => 400 ] );
					}

					return $value;
				},
				'sanitize_callback' => [ $this, 'sanitize_callback' ],
			],
			'failed_reason' => [
				'description'       => __( 'Why this particular order has failed.', 'event-tickets' ),
				'required'          => false,
				'type'              => 'string',
				'validate_callback' => static function ( $value ) {
					if ( ! is_string( $value ) ) {
						return new WP_Error( 'rest_invalid_param', 'The failed reason argument must be a string.', [ 'status' => 400 ] );
					}

					return $value;
				},
				'sanitize_callback' => [ $this, 'sanitize_callback' ],
			],
		];
	}