Per Matt Benson's email on the list:

Consider InvalidGroupConversionInPropertyLevelOverridingTest#testGroupConversionsAreAdditiveAndExceptionIsThrownForMultipleConversionWithSameSource():

This test purports to enforce that a ValidationException is thrown because a property specifies multiple group conversions from the Default group. However, the example actually specifies one via the annotated getter, and the other via the XML-configured field. I can't find that the spec is perfectly clear on this, but it is clear that a property should be accessed using the mechanism of constraint declaration. I don't recall where, but the TCK tests proper validation of field vs. getter even when the objects returned are different. I would therefore argue that there could be some legitimate reason to apply a different group conversion to field vs. getter, and that the test case should be changed to specify the XML constraint via getter as does the User class definition overridden.