My only goal is to simplify current usage and the simplest step in that direction would be to add Default as default to ConvertGroup.
Now I'm not quite sure, after a finer grained look, that @Validated and @ConvertGroup should be used for the same use case.
The use case is, as described in the issue description, to specify group to use while validating a method. Maybe a new annotation should be defined? @ValidationGroup(Update.class)?