code: public String resolveTimeZoneId(String zoneId) {
      String alias = _CalendarUtils.getTimeZoneAlias(zoneId);
      if (alias != null) {
        zoneId = alias;
      }
      alias = TimeZoneAliases.getAlias(zoneId);
      if (alias != null) {
        zoneId = alias;
      }
      return zoneId;
    }
docs: Check if the zoneId has an alias in the CLDR data.