code: public static void initMocks(Object owner) {
      // Create a new bridge and register built-in type providers
      bridge = new Bridge();
      for (Entry<Class<?>, FakeProvider<?>> entry : DEFAULT_FAKE_PROVIDERS.entrySet()) {
        useProviderForType(entry.getKey(), entry.getValue());
      }
  
      // Install the bridge and populate mock fields
      boolean success = false;
      try {
        setGwtBridge(bridge);
        registerGwtMocks(owner);
        MockitoAnnotations.initMocks(owner);
        success = true;
      } finally {
        if (!success) {
          tearDown();
        }
      }
    }
docs: Causes all calls to GWT.create to be intercepted to return a mock or fake
  object, and populates any {@link GwtMock}-annotated fields with mockito
  mocks. This method should be usually be called during the setUp method of a
  test case. Note that it explicitly calls
  {@link MockitoAnnotations#initMocks}, so there is no need to call that
  method separately. See the class description for more details.
  
  @param owner class to scan for {@link GwtMock}-annotated fields - almost
  always "this" in unit tests