docs: private void doConnect() throws SessionTimeOutException{
          long to = getConnectTimeOut();
  
          if(clientSocket.isConnected()){
              ErrorCode ec = sendConnectProtocol(to);
              // CONNECTION_LOSS means client data is inconsistence with server. now we check the last dxid of client.
              // if dxid of the client is bigger than server actual dxid, return CONNECTION_LOSS.
              if(ErrorCode.SESSION_EXPIRED.equals(ec) || ErrorCode.CONNECTION_LOSS.equals(equals(ec))){
                  LOGGER.info("Session Expired, cleanup the client session.");
                  cleanupSession();
              }
          }
      }