docs: public void setZoneRetainFields(DateTimeZone newZone) {
          newZone = DateTimeUtils.getZone(newZone);
          DateTimeZone originalZone = DateTimeUtils.getZone(getZone());
          if (newZone == originalZone) {
              return;
          }
          
          long millis = originalZone.getMillisKeepLocal(newZone, getMillis());
          setChronology(getChronology().withZone(newZone));  // set via this class not super
          setMillis(millis);
      }