RESTWebservices and GUI Framework PinPoints:
1. Based on my experience with GWT/Vaadin and REST Webservice dont ever treat JAXB Beans as a Model in the UI layer.
2. Create a separate model objects in the UI Layer and have 'Has-A' relationship with the JAXB Model.
3. Having separate model objects in UI Layer separates the logic from the JAXB Beans and the UML Model generated.
4. If the UML Model generated beans implemented default version of equals()/hashcode() methods this will have impact on the UI layer as well.
5. Maintaining/Versioning of the UML will impact the JAXB beans which will break the UI layer.
In the UI layer, have a separate model which will allow to have greater flexibility in terms of UI handling with respect to data formats, rendering, etc...