code: public function getData()
      {
          $reference = new FluidXml(false);
          $reference->add($this->getTransactionReference());
  
          return [
              'password'             => $this->getPassword(),
              'userId'               => $this->getUserId(),
              'merchantId'           => $this->getMerchantId(),
              'transactionReference' => $reference
          ];
      }
docs: Complete purchase data
  @return array