code: public int toSecondOfDay() {
          int total = hour * SECONDS_PER_HOUR;
          total += minute * SECONDS_PER_MINUTE;
          total += second;
          return total;
      }
docs: Extracts the time as seconds of day,
  from {@code 0} to {@code 24 * 60 * 60 - 1}.
  
  @return the second-of-day equivalent to this time