prevstate_retained_test.dart

@Factory()
UiFactory<FooProps> Foo;

@Props()
class FooProps extends UiProps {}

@State()
class FooState extends UiState {
  Object stateValue;
}

@Component()
class FooComponent extends UiStatefulComponent<FooProps, FooState> {
  @override
  getInitialState() => newState()..stateValue = new TestRetainedClass();

  @override
  componentDidMount() {
    super.componentWillMount();

    setState(newState()..stateValue = null);
  }

  @override
  render() {
    return Dom.div()();
  }
}

class TestRetainedClass {}