}
}
HandlerRegistration handlerRegistration = null;
if (widget instanceof HasValue) {
handlerRegistration = ((HasValue) widget).addValueChangeHandler(new ValueChangeHandler() {
@Override
public void onValueChange(ValueChangeEvent event) {
Object oldValue = proxy.get(property);
Object newValue = toModelValue(propertyTypes.get(property).getType(), widget, event.getValue(), converter);
proxy.set(property, newValue);