NameCallback nc = (NameCallback) cb;
                String userDomain = this.getSpecifiedUserDomain();
                if ( this.getUsername() != null && userDomain != null ) {
                    nc.setName(this.getUsername() + "@" + userDomain);
                }
            }
            else if ( cb instanceof PasswordCallback ) {
                PasswordCallback pc = (PasswordCallback) cb;