code: public String getSystemMessageId() {
          SIBUuid8 u = getSystemMessageSourceUuid();
          if (u != null) {
              StringBuffer buff = new StringBuffer(u.toString());
              buff.append(MfpConstants.MESSAGE_HANDLE_SEPARATOR);
              buff.append(Long.toString(getSystemMessageValue()));
              return buff.toString();
          }
          else {
              return null;
          }
      }
docs: /*
  Get the unique system message id from the message header.
  
  NOTE: WPS have a requirement that the returned value has a length of
  no more than 255. Currently it is substantially shorter than that, but
  it needs to be borne in mind if anyone has any grandiose ideas for the
  SystemMessageId in the future.
  
  Javadoc description supplied by SIBusMessage interface.