Hi again,
I just verified the ElementCollection and the problem is exactly the same as with @OneToMany still the same shared reference Hibernate exception. And still my fixed CollectionKey (see the zip file and the org/ folder, there is also a readme there) solves this problem.

So we still have the problem here.

I was thinking again about the possible solutions and I see three:
*1. *Modify the CollectionKey behaviour to take the PK of collection container entity - as I did in the fix.
I don't see yet any disadventages but I would guess that it might break the circular dependency detection as the comment in Collections.java:178 says:

// The CollectionEntry.isReached() stuff is just to detect any silly users
// who set up circular or shared references between/to collections.

*2. * Add an annotation which may disable the shared collection check at Collections.java:180 if a user knows what he is doing.
*3. * And the last which I already mentioned: Maybe this check for shared collections at Collections.java:180 should be disabled if the involved collections are marked non insertable and non updateable.

What do you think?