FtpServerFactory factory = new FtpServerFactory();
        ListenerFactory lisnerFactory = new ListenerFactory();
        lisnerFactory.setPort(port);
        factory.addListener("default", lisnerFactory.createListener());

        if (username != null) {
            UserManager userManager = factory.getUserManager();
            BaseUser ftpUser = new BaseUser();
            ftpUser.setName(username);