docs: public static String fromUnixtime(long unixtime, String format, TimeZone tz) {
  		SimpleDateFormat formatter = FORMATTER_CACHE.get(format);
  		formatter.setTimeZone(tz);
  		Date date = new Date(unixtime * 1000);
  		try {
  			return formatter.format(date);
  		} catch (Exception e) {
  			LOG.error("Exception when formatting.", e);
  			return null;
  		}
  	}