1.0beta6: @POST method dies

When I invoke a @POST method I receive an internal server error. There was no problem when using 1.0beta5.

This is the class definition:
@Path("/kundenverwaltung")
@Produces(APPLICATION_XML)
@Consumes(APPLICATION_XML)
public class KundenverwaltungResource {
@Context
private UriInfo uriInfo;

@Path("/kunden")
@POST
@Produces
public Response createKunde(Kunde kunde) throws KundeException, KundeDuplikatException

...
}

This is the contents of server.log (nothing more at the end):
...
2008-09-10 16:50:57,125 INFO [org.jboss.system.server.Server] JBoss (MX MicroKernel) [4.2.3.GA (build: SVNTag=JBoss_4_2_3_GA date=200807181417)] Started in 21s:953ms
2008-09-10 16:51:06,927 DEBUG [org.jboss.resteasy.core.SynchronousDispatcher] PathInfo: /kundenverwaltung/kunden

The server response will be provided as a screenshot of the Eclipse plugin http4e.