code: @Override
      public void getOffset(long date, boolean local, int[] offsets)  {
          if (finalZone != null && date >= finalStartMillis) {
              finalZone.getOffset(date, local, offsets);
          } else {
              getHistoricalOffset(date, local,
                      LOCAL_FORMER, LOCAL_LATTER, offsets);
          }
      }
docs: TimeZone API.