code: private void initializeDefaultCenturyStart(long baseTime) {
          defaultCenturyBase = baseTime;
          // clone to avoid messing up date stored in calendar object
          // when this method is called while parsing
          Calendar tmpCal = (Calendar)calendar.clone();
          tmpCal.setTimeInMillis(baseTime);
          tmpCal.add(Calendar.YEAR, -80);
          defaultCenturyStart = tmpCal.getTime();
          defaultCenturyStartYear = tmpCal.get(Calendar.YEAR);
      }
docs: /* Initialize defaultCenturyStart and defaultCenturyStartYear by base time.
  The default start time is 80 years before the creation time of this object.