code: @Override
    public String shutdown() {
      client.shutdown();
      String status;
      try {
        status = client.getStatusCodeReply();
      } catch (JedisException ex) {
        status = null;
      }
      return status;
    }
docs: Synchronously save the DB on disk, then shutdown the server.
  <p>
  Stop all the clients, save the DB, then quit the server. This commands makes sure that the DB
  is switched off without the lost of any data. This is not guaranteed if the client uses simply
  {@link #save() SAVE} and then {@link #quit() QUIT} because other clients may alter the DB data
  between the two commands.
  @return Status code reply on error. On success nothing is returned since the server quits and
  the connection is closed.