docs: 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;
          }
      }