code: public void initialize(Configuration conf, FSClusterStats stats, NetworkTopology clusterMap,
        HostsFileReader hostsReader, DNSToSwitchMapping dnsToSwitchMapping, FSNamesystem ns) {
      this.nameSystem = ns;
      super.initialize(conf, stats, clusterMap, hostsReader, dnsToSwitchMapping, ns);
    }
docs: {@inheritDoc}