Merge with reference fails if entity is associated to a column (non id)

[DavideD]

See the following tests:

• https://github.com/hibernate/hibernate-reactive/blob/main/hibernate-reactive-core/src/test/java/org/hibernate/reactive/LazyUniqueKeyTest.java#L71
• https://github.com/hibernate/hibernate-reactive/blob/main/hibernate-reactive-core/src/test/java/org/hibernate/reactive/EagerUniqueKeyTest.java#L71

I've created the following testcase for ORM: hibernate/hibernate-orm#6239
Waiting for ORM to fix https://hibernate.atlassian.net/browse/HHH-16298

(Follows #1498)

[blafond]

@DavideD I changed the EntityTypes.getIdentifier() method to mimic your changes in ORM's EntityType. I also tweaked our failing merge tests to mimic the new ORM merge test.

lates: https://github.com/blafond/hibernate-reactive/commits/1504-merge-reference

Now all Eager & Lazy merge tests fail because the initializer.getImplementation() forces a call to the reactive session's immediateLoad().

I'm assuming I need to route it to our reactiveImmediateLoad() to make this work, but right now it's only called in reactiveFetch()?

[DavideD]

I'm assuming I need to route it to our reactiveImmediateLoad() to make this work, but right now it's only called in reactiveFetch()?

I haven't checked the code yet, but sounds right