Cascade update does not remove existing link records

[andriy-dmytruk]

Expected Behavior

In the AssignedUuidManyToManyPersistSpec.groovy#L62 test, it seems like the update is not overwritting the courses, instead it adds courses again:

        c1.name = 'Mathematics'
        s3.courses = [c1]
        studentRepository.update(s3) // This does not remove old courses, but instead adds new ones.
        def found2 = studentRepository.findById(s3.id).orElse(null)

Despite calling update with the same course, the course gets added again and is duplicated.

We have added primary key to the join table columns and this test started failing because it wanted to add the same row twice breaking the primary key constraint.

Actual Behaviour

The test is breaking

Steps To Reproduce

Showed in this PR: #3632, as it adds primary key to mapping tables.

Environment Information

No response

Example Application

No response

Version

5.0.0