code: void formatHours(StringBuilder b, ZonedDateTime d, int width, boolean twelveHour) {
      int hours = d.getHour();
      if (twelveHour && hours > 12) {
        hours = hours - 12;
      }
      if (twelveHour && hours == 0) {
        hours = 12;
      }
      zeroPad2(b, hours, width);
    }
docs: Format the hours in 12- or 24-hour format, optionally zero-padded.