Yes, 4.3.1.Final. I cannot move up until I upgrade Spring because of changes to the packaging structure in HibVal.

In any case: yes, Spring message sources can be configured to return "messages.mymessage" if messages.mymessage doesn't exist in the language file. For me, this is the preferred setting because I don't want to get a 500 error just because someone made a little mistake in a language file.