code: public void timestamp(String name, ZonedDateTime value) {
  		Counter counter = get(name, CounterType.Timestamp);
  		counter.setTime(value != null ? value : ZonedDateTime.now(ZoneId.of("Z")));
  		update();
  	}
docs: Records the given timestamp.
  
  @param name  a counter name of Timestamp type.
  @param value a timestamp to record.