Ok, downloaded the source and debugged a little bit.
The real problem is, that in the class SecurableObjectHolder (line 117) the class JCEEncryptor can not be casted to Securable (class cast exception).
But JCEEncryptor implements Securable.
Cause of this I think this is a Classloader-Issue of the JBoss.
For toplink this is a non-issue.
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