Propagation of validation errors to CustomField

Hello,
I'm currently moving to vaadin 8.0.5. I have a CustomField which I bind to some method and a validator.
The problem is now, that I do not understand how to catch the validation errors and show them on my field, see the following snippet:

class Bean {
   String name;
   public String getName() { return name; }
   public void setName(String name) { this.name = name; }
}

class TestField extends CustomField<String> {
   TextField field = new TextField();
   @Override protected Component initContent() { return field; }
   @Override protected void doSetValue(String s) { field.setValue(s); }
   @Override public String getValue() { return field.getValue(); }
}

TextField field = new TextField();
TestField custom_field = new TestField();

new Binder<Bean>().forField(field)
.withValidator(s -> false, "this error is visible")
.bind(Bean::getName,Bean::setName);

new Binder<Bean>().forField(custom_field)
.withValidator(s -> false, "this error is not visible")
.bind(Bean::getName,Bean::setName);

The standard TextField just displays the validation error as expected, the CustomField however shows no error indicator...
What am I missing?

Thank you very much!

Edit: So, i've found the 'ValidationStatusHandler', but this does not trigger.... weird...

new Binder<Bean>().forField(custom_field)
.withValidator(s -> false, "this error is not visible")
.withValidationStatusHandler(System.err::println)
.bind(Bean::getName,Bean::setName);

Edit: Since I did not get a response here, I've created a bug report: https://github.com/vaadin/framework/issues/9278

Meanwhile, I think I've found the missing peace. Overwriting the following methods did the trick:

@Override
public void setComponentError(ErrorMessage componentError) {
    super.setComponentError(componentError);
    field.setComponentError(componentError);
}
@Override
public Registration addValueChangeListener(ValueChangeListener<String> listener) {
    return field.addValueChangeListener(listener);
}