String logMessage() {
    if (logMessage == null) {
      StringBuilder builder = new StringBuilder(64);
      builder
          .append(DateTimeFormatter.ISO_INSTANT.format(Instant.ofEpochMilli(time)))
          .append(" [")
          .append(Thread.currentThread().getName())
          .append("] ")
          .append(level.name())
          .append(' ')
          .append(logger)
          .append(" - ");

      if (arguments == null) builder.append(message);
      else builder.append(Strings.format(message, arguments));

      builder.append(System.lineSeparator());
      if (exception != null) builder.append(Exceptions.stackTrace(exception));

      logMessage = builder.toString();
    }
    return logMessage;
  }
 @RequestMapping(value = "/", method = RequestMethod.GET)
 @ResponseBody
 public String tell() {
   return DateTimeFormatter.ISO_INSTANT.format(ZonedDateTime.now(clock));
 }