code: @Override
      public void onModuleLoad() {
          Button button = new Button("Get Greeting");
          button.addClickHandler(new ClickHandler() {
              @Override
              public void onClick(ClickEvent event) {
                  getGreeting();
              }
          });
          RootPanel.get().add(button);
          RootPanel.get().add(new Label("Name:"));
          final TextBox nameInput = new TextBox();
          RootPanel.get().add(nameInput);
          Button customButton = new Button("Get Custom Greeting");
          customButton.addClickHandler(new ClickHandler() {
              @Override
              public void onClick(ClickEvent event) {
                  getCustomGreeting(nameInput.getValue());
              }
          });
          RootPanel.get().add(customButton);
      }
docs: This is the entry point method.