code: private PayloadTemplateMessageBuilder parsePayloadElement(Element messageElement) {
          PayloadTemplateMessageBuilder messageBuilder = null;
          
          // parse payload with xs-any element
          Element payloadElement = DomUtils.getChildElementByTagName(messageElement, "payload");
          if (payloadElement != null) {
              messageBuilder = new PayloadTemplateMessageBuilder();
  
              if (messageElement.hasAttribute("name")) {
                  messageBuilder.setMessageName(messageElement.getAttribute("name"));
              }
  
              List<Element> payload = DomUtils.getChildElements(payloadElement);
              if (CollectionUtils.isEmpty(payload)) {
                  messageBuilder.setPayloadData("");
              } else {
                  messageBuilder.setPayloadData(PayloadElementParser.parseMessagePayload(payload.get(0)));
              }
          }
          
          return messageBuilder;
      }
docs: Parses the xs:any payload elements nested in message element.
  @param messageElement