in Hibernate 5 we had an entity with composite pripary key, @IdClass annotation was used there. After upgrade to H6 (6.2.0.CR4) we face an issue where part of primary key is not returned when querying. It then causes following issue:

org.hibernate.HibernateException: identifier of an instance of SomeEntity was altered from SomeEntity.Key [user=null, identityProvider=idp] to SomeEntity.Key [user=1, identityProvider=idp]

I've created a reproducer: https://github.com/hibernate/hibernate-test-case-templates/compare/main...vramik:hibernate-test-case-templates:kc-19323-entity-key-not-returned