Group by problem with Hibernate

Recently had a small problem that the group by function didn't work, if I added a subtable to the query. The GROUP BY expression did not match any longer.

Seems a long standing problem with Hibernate.

References

Java Persistence with Hibernate, page 392

Christian Bauer, Gavin King, Gary Gregoy

HH-1615 - GROUP BY entity does not work

https://hibernate.atlassian.net/browse/HHH-1615

HH2436 - Allow grouping by entity reference (per JPA spec)

https://hibernate.atlassian.net/browse/HHH-2436