protected function fillTransaction(SimpleXMLElement $xml)
 {
     $hpsPopulator = new HpsTxnPopulator();
     $hpsPopulator->setReturnUrl($this->returnUrl)->setExpiryUrl($this->expiryUrl)->setPageSetId($this->pageSetId);
     $detailsPopulator = new TxnDetailsPopulator();
     $detailsPopulator->setReference($this->reference)->setAmount($this->amount);
     $hpsPopulator->createElement($xml->addChild('HpsTxn'));
     $detailsPopulator->createElement($xml->addChild('TxnDetails'));
 }
 protected function innerCreateElement(SimpleXMLElement $xml)
 {
     parent::innerCreateElement($xml);
     $this->threeDPopulator->createElement($xml->addChild('ThreeDSecure'));
 }