docs: public InetSocketAddress getNextDirectoryServer(){
  
          index = index + 1;
          if(index == servers.size()){
              index = 0;
          }
          InetSocketAddress unresolved = servers.get(index);
  
  //        List<InetSocketAddress> resolved = null;
  //        try {
  //            InetAddress[] addresses = InetAddress.getAllByName(unresolved.getHostName());
  //            for(InetAddress address : addresses){
  //                if(resolved == null){
  //                    resolved = new ArrayList<InetSocketAddress>();
  //                }
  //                resolved.add(new InetSocketAddress(address.getHostAddress(), unresolved.getPort()));
  //            }
  //        } catch (UnknownHostException e) {
  //            LOGGER.error("Resolve the Directory Server failed, host=" + unresolved.getAddress().toString() + " - " + e.getMessage());
  //        }
  //
  //        if(resolved == null){
  //            return Collections.emptyList();
  //        }
          return new InetSocketAddress(unresolved.getHostName(), unresolved.getPort());
      }