Brett Meyer commented on an issue
Hibernate ORM / Bug HHH-7226
Result transformer set on Query is ignored
When something like this is done:

String queryStr = "some query";
Query query = getSession().createQuery(queryStr);
query.setResultTransformer(DistinctResultTransformer.INSTANCE);

then query.list() is not transformed by given transformer.

Workaround exists:

DistinctResultTransformer.INSTANCE.transformList(query.list());