/**
* @param \AdamStipak\Webpay\PaymentRequest $request
* @return array
*/
public function createPaymentParam(PaymentRequest $request)
{
// digest request
$request->setMerchantNumber($this->merchantNumber);
$params = $request->getParams();
$request->setDigest($this->signer->sign($params));
return $request->getParams();
}