It seems that if you have enough aliases in the ref-alias list of a polymorphic relationship, then you get an OutOfMemoryError.
By changing line 13/14 of Father.cmp.xml you can hit/miss the OOME. If you turn -verbose:true on though, you see the memory uitlisation is quite high even if you dont get an OOME.
Code attached
CMP-304, which has been fixed. After the fix, the code attached works as well. Can you validate this on your side?