protected function getTransactionReference( \Aimeos\MShop\Order\Item\Base\Iface $base )
	{
		$code = $this->getServiceItem()->getCode();
		$service = $base->getService( \Aimeos\MShop\Order\Item\Base\Service\Base::TYPE_PAYMENT, $code );

		return $service->getAttribute( 'TRANSACTIONID', 'payment/omnipay' );
	}