code: public byte[] convertToXmlByteArray(
              RequestPaymentConfiguration requestPaymentConfiguration) {
          XmlWriter xml = new XmlWriter();
          xml.start("RequestPaymentConfiguration", "xmlns",
                  Constants.XML_NAMESPACE);
  
          Payer payer = requestPaymentConfiguration.getPayer();
          if (payer != null) {
              XmlWriter payerDocumentElement = xml.start("Payer");
              payerDocumentElement.value(payer.toString());
              payerDocumentElement.end();
          }
          xml.end();
          return xml.getBytes();
      }
docs: Converts the specified request payment configuration into an XML byte
  array to send to Amazon S3.
  
  Sample XML:
  <RequestPaymentConfiguration xmlns="http://s3.amazonaws.com/doc/2006-03-01/">
  <Payer>Requester</Payer>
  </RequestPaymentConfiguration>
  
  @param requestPaymentConfiguration
  The request payment configuration request to convert..
  @return The XML byte array representation.