I'm getting the same exception. In my case, the problem seems to be the SpringLifecycleInterceptor interceptor class. Only after adding the snowdrop-deployers.jar to my .ear the problem dissapear although I have already install snowdrop in the modules folder, and then added the extension org.jboss.snowdrop to my configuration.
I suppose adding the snowdrop jar to my ear isn't the right solution, so I'l glad to hear to the right one!