code: public final void register(final TimeZone timezone, boolean update) {
          if (update) {
              try {
                  // load any available updates for the timezone..
                  timezones.put(timezone.getID(), new TimeZone(timeZoneLoader.loadVTimeZone(timezone.getID())));
              } catch (IOException | ParserException | ParseException e) {
                  Logger log = LoggerFactory.getLogger(TimeZoneRegistryImpl.class);
                  log.warn("Error occurred loading VTimeZone", e);
              }
          } else {
              timezones.put(timezone.getID(), timezone);
          }
      }
docs: {@inheritDoc}