code: protected String getRebootMessage (String key, int minutes)
      {
          String msg = getCustomRebootMessage();
          if (StringUtil.isBlank(msg)) {
              msg = "m.reboot_msg_standard";
          }
  
          return MessageBundle.compose(key, MessageBundle.taint("" + minutes), msg);
      }
docs: Composes the given reboot message with the minutes and either the custom or standard details
  about the pending reboot.