code: public static String getTimeoutMessage(long timeout, TimeUnit unit) {
          return String.format("Timeout of %d %s reached", timeout, requireNonNull(unit, "unit"));
      }
docs: Utility method that produce the message of the timeout.
  @param timeout the maximum time to wait.
  @param unit    the time unit of the timeout argument
  @return formatted string that contains the timeout information.