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a20eb8d1e9
Given an entity with auto-filled id fields (annotated with @GeneratedValue, with null as initial value), when inserting it using Hibernate, the id fields will be filled with non-nulls even if the transaction fails. If the same entity instance is used again in a retry, Hibernate mistakes it as a detached entity and raises an error. The work around is to make a new copy of the entity in each transaction. This PR applies this pattern to affected entity types. We considered applying this pattern to JpaTransactionManagerImpl's insert method so that individual call sites do not have to change. However, we decided against it because: - It is unnecessary for entity types that do not have auto-filled id - The JpaTransactionManager cannot tell if copying is cheap or expensive. It is better exposing this to the user. - The JpaTransactionManager needs to know how to clone entities. A new interface may need to be introduced just for a handful of use cases.