code: public static void createAsync(final GWTVizPlotClient client) {
          GWT.runAsync(new RunAsyncCallback() {
              public void onFailure(Throwable err) {
                  client.onUnavailable();
              }
  
              public void onSuccess() {
                  if (instance == null) {
                      instance = new GWTVizPlot();
                  }
                  client.onSuccess(instance);
              }
          });
      }
docs: Access the module's instance.  The callback
  runs asynchronously, once the necessary
  code has downloaded.