code: public static UResourceBundle openOlsonResource(UResourceBundle top, String id)
      {
          UResourceBundle res = null;
          int zoneIdx = getZoneIndex(id);
          if (zoneIdx >= 0) {
              try {
                  if (top == null) {
                      top = UResourceBundle.getBundleInstance(
                              ICUData.ICU_BASE_NAME, ZONEINFORESNAME, ICUResourceBundle.ICU_DATA_CLASS_LOADER);
                  }
                  UResourceBundle zones = top.get(kZONES);
                  UResourceBundle zone = zones.get(zoneIdx);
                  if (zone.getType() == UResourceBundle.INT) {
                      // resolve link
                      zone = zones.get(zone.getInt());
                  }
                  res = zone;
              } catch (MissingResourceException e) {
                  res = null;
              }
          }
          return res;
      }
docs: Given an ID and the top-level resource of the zoneinfo resource,
  open the appropriate resource for the given time zone.
  Dereference links if necessary.
  @param top the top level resource of the zoneinfo resource or null.
  @param id zone id
  @return the corresponding zone resource or null if not found