In Delegate class getReplyGroup method is not thread safe:
    private ReplyGroup getReplyGroup (ClientConnection connectionToUse)
This part of code can cause that if 2 threads are works in parallel one can works with ReplyGroup that didn't pass the postInit method:
            ReplyGroup g = new ReplyGroup (this, profile);
            group = groups.putIfAbsent (profile, g);
            if (group == null)
            {
                group = g;
                group.postInit();
            }

Why the postInit method is not part of the constructor? This would have solve the problem?

See below stack trace of the exception I got because of this problem:
(got NullPointerException)

at org.omg.CORBA.portable.ObjectImpl._invoke(ObjectImpl.java:475)
                at org.jacorb.orb.Delegate.invoke(Delegate.java:1232)
                at org.jacorb.orb.Delegate.invoke_internal(Delegate.java:1244)
                at org.jacorb.orb.Delegate._invoke_internal(Delegate.java:1415)
                at org.jacorb.orb.ReplyGroup.addHolder(ReplyGroup.java:92)

Thanks.