docs: public static long unixTimestamp(String dateStr, String format, TimeZone tz) {
  		long ts = parseToTimeMillis(dateStr, format, tz);
  		if (ts == Long.MIN_VALUE) {
  			return Long.MIN_VALUE;
  		} else {
  			// return the seconds
  			return ts / 1000;
  		}
  	}