How to use Groups with JSR 303 in Vaadin 7?

I migrated the Vaadin Tutorial to Vaadin 7b11. I changed the old PersonForm to be a VerticalLayout using a FormLayout with BeanFieldGroup and JSR 303 -Validation.
The (Default Group) validation takes place as intended on “Save” but also on “Add Contact”. Every time a new empty Person Bean is set a validation takes place in the rendering Process (I think the method getErrorMessages calls validate). So e.g. a constraint like

@Size(min = 2, max = 20)
private String firstName = ""; 

shows an error on an empty Bean.
The solution with JSR 303 that comes to my mind is using a group for the different lifecycle steps of the Person Bean. In state “new” no validation is done, in state “created” some validation is done and so on. So, my question is whether there already is the possibility to change the validate-call to a validate-call that uses the state (Group) the bean is in.

My workaround today is that I remove all validators after I set the new bean and add them again in the save-method, but that’s not too nice.