code: private void readObject(ObjectInputStream stream)
              throws IOException, ClassNotFoundException {
          stream.defaultReadObject();
          if (gdate == null) {
              gdate = (BaseCalendar.Date) gcal.newCalendarDate(getZone());
              cachedFixedDate = Long.MIN_VALUE;
          }
          setGregorianChange(gregorianCutover);
      }
docs: Updates internal state.