public void onSuccess(SimpleValueProxy response) {
final SimpleValueProxy original = checkSerialization(response);
SimpleFooRequest req = simpleFooRequest();
final SimpleValueProxy value = req.edit(response);
value.setShouldBeNull("Hello world");
SimpleFooProxy foo = req.create(SimpleFooProxy.class);
foo.setSimpleValue(value);
req.echo(foo).fire(new Receiver<SimpleFooProxy>() {
@Override
public void onConstraintViolation(Set<ConstraintViolation<?>> errors) {
assertEquals(1, errors.size());