code: private synchronized ZNames loadMetaZoneNames(String mzID) {
          ZNames mznames = _mzNamesMap.get(mzID);
          if (mznames == null) {
              ZNamesLoader loader = new ZNamesLoader();
              loader.loadMetaZone(_zoneStrings, mzID);
              mznames = ZNames.createMetaZoneAndPutInCache(_mzNamesMap, loader.getNames(), mzID);
          }
          return mznames;
      }
docs: Returns a set of names for the given meta zone ID. This method loads
  the set of names into the internal map and trie for future references.
  @param mzID the meta zone ID
  @return An instance of ZNames that includes a set of meta zone display names.