I have *exactly* the same problem. Do you have a solution meanwhile?
I have a similar problem.
I cannot get a Corba object out of org.omg.CORBA.Object _is_a metgod
The error is the same. Object is immtable in com.sun.corba.se.internal.ior.FreezableList add(object) method
A workaround found in Sun's Java Forum:
does not help either
I see its an old issue, so if anyone knows, please drop a line.