Context: In my pure JPA-compliant app I have a bidirectional 1:n relationship expressed via a @ManyToOne foreign key on the child entity class, and a @OneToMany collection of children on the parent entity class. Both entity classes use optimistic locking via a @Version field.
Problem: When I create a new child entity, and add the entity to the collection on the parent, the parent's version changes, causing OptimisticLockingException when concurrently creating child entities. As the parent is the non-owning side of the relationship, this violates the JPA spec.
JPA 2.0 states the following (Section 3.4.2):
The version attribute is updated by the persistence provider runtime when the object is written to the database. All non-relationship fields and properties and all relationships owned by the entity are included in version checks.
What the JPA spec says is reasonable, as the parent entity's associated DB record does not change at all in this case (besides the bad version increment).
I am attaching a simple test case reproducing the problem.
This was previously described here: http://stackoverflow.com/a/5259163
It looks like no defect was created at the time.
A workaround, as mentioned in the article, is to specify @OptimisticLock(exclude = true) on the @OneToMany collection field. However, this pollutes a pure JPA app and makes it non-portable.
Hibernate 4.1.0 or 3.6.8., SQL Server or H2 Database Engine