code: private static TzServer getTzServer(final String url) throws TimezonesException {
      synchronized (tzServers) {
        TzServer svr = tzServers.get(url);
  
        if (svr != null) {
          return svr;
        }
  
        svr = new TzServer(url);
        tzServers.put(url, svr);
  
        return svr;
      }
    }
docs: /* ====================================================================
  private methods
  ====================================================================