I'm not sure I understand why the referenced JIRA is relevant. For model validation (which is what we are doing), groups applied to a @Valid doesn't make sense because the constraints on the target property's type will contain the groups. However for method validation (as used in the referred to JIRA), it looks like @Valid is used as a marker to instruct Spring MVC to perform model validation but there is no facility for specifying groups in this case (as I understand).
For SWF, an attribute 'validation-groups' or similar allows us to specify the groups for model validation.
I think the feature should allow multiple groups to be specified as unqualified names which refer either to inner types defined within the specified model object or types defined within the same package as the model object.