org.jboss.com.sun.corba.se.impl.javax.rmi.PortableRemoteObject#narrow() has a catch (Exception error) block in it which wraps all exceptions in a ClassCastException. However, there should be a second catch block which catches RuntimeException and rethrows them verbatim, in order to avoid confusing incorrect error messages.

In particular, you can get a ClassCastException whose cause is another ClassCastException.

Problem found in 1.0.4.Final; no version for this exists in the JIRA schema however.