code: private static synchronized String[] getZoneIDs() {
          if (ZONEIDS == null) {
              try {
                  UResourceBundle top = UResourceBundle.getBundleInstance(
                          ICUData.ICU_BASE_NAME, ZONEINFORESNAME, ICUResourceBundle.ICU_DATA_CLASS_LOADER);
                  ZONEIDS = top.getStringArray(kNAMES);
              } catch (MissingResourceException ex) {
                  // throw away..
              }
          }
          if (ZONEIDS == null) {
              ZONEIDS = new String[0];
          }
          return ZONEIDS;
      }
docs: /*
  ICU frequently refers the zone ID array in zoneinfo resource