Based on the stack trace TopLink is stuck processing from a XtoMany mapping to a XtoOne mapping and back to the same XtoMany mapping. The only way this could happen is if TopLink was getting a new instance of an object everytime it accessed a related object.
Have you tried reducing the example to a single set of mappings that reproduce the problem? You could also debug the loop to see what instances of objects are being processed in this code.
--Gordon
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