private void login() {
final Button button = new Button("Log in to get started");
button.addClickHandler(new ClickHandler() {
@Override
public void onClick(ClickEvent event) {
new ClientOAuth2Login(CLIENT_ID)
.withScopes(UrlshortenerAuthScope.URLSHORTENER)
.login(new Receiver<String>() {
@Override
public void onSuccess(String accessToken) {
initialize(accessToken);