code: protected int computeMillisInDay() {
          // Do the time portion of the conversion.
  
          int millisInDay = 0;
  
          // Find the best set of fields specifying the time of day.  There
          // are only two possibilities here; the HOUR_OF_DAY or the
          // AM_PM and the HOUR.
          int hourOfDayStamp = stamp[HOUR_OF_DAY];
          int hourStamp = Math.max(stamp[HOUR], stamp[AM_PM]);
          int bestStamp = (hourStamp > hourOfDayStamp) ? hourStamp : hourOfDayStamp;
  
          // Hours
          if (bestStamp != UNSET) {
              if (bestStamp == hourOfDayStamp) {
                  // Don't normalize here; let overflow bump into the next period.
                  // This is consistent with how we handle other fields.
                  millisInDay += internalGet(HOUR_OF_DAY);
              } else {
                  // Don't normalize here; let overflow bump into the next period.
                  // This is consistent with how we handle other fields.
                  millisInDay += internalGet(HOUR);
                  millisInDay += 12 * internalGet(AM_PM); // Default works for unset AM_PM
              }
          }
  
          // We use the fact that unset == 0; we start with millisInDay
          // == HOUR_OF_DAY.
          millisInDay *= 60;
          millisInDay += internalGet(MINUTE); // now have minutes
          millisInDay *= 60;
          millisInDay += internalGet(SECOND); // now have seconds
          millisInDay *= 1000;
          millisInDay += internalGet(MILLISECOND); // now have millis
  
          return millisInDay;
      }
docs: Compute the milliseconds in the day from the fields.  This is a
  value from 0 to 23:59:59.999 inclusive, unless fields are out of
  range, in which case it can be an arbitrary value.  This value
  reflects local zone wall time.
  @deprecated This method suffers from a potential integer overflow and may be removed or
  changed in a future release. See <a href="http://bugs.icu-project.org/trac/ticket/11632">
  ICU ticket #11632</a> for details.