BooleanRadioGroupPlugin: Value is not stored when underlying property doesn't exist

The problem is that the BooleanRadioGroupPlugin does not store the value when a new document has just been created and the document is being edited & saved for the first time. Mu guess is that this happens because the backing JCR property is not yet present on the document. If you save the document, and edit the document again, then the boolean radio field can be successfully changed and is stored properly.