code: public String convert(String messagePayload) {
          initialize();
  
          // check if we already have XHTML message content
          if (messagePayload.contains(XHTML_DOCTYPE_DEFINITION)) {
              return messagePayload;
          } else {
              String xhtmlPayload;
              StringWriter xhtmlWriter = new StringWriter();
              tidyInstance.parse(new StringReader(messagePayload), xhtmlWriter);
  
              xhtmlPayload = xhtmlWriter.toString();
              xhtmlPayload = xhtmlPayload.replaceFirst(W3_XHTML1_URL, "org/w3/xhtml/");
              return xhtmlPayload;
          }
      }
docs: Converts message to XHTML conform representation.
  @param messagePayload
  @return