Code improvement suggestion in CollectionEntry.postInitialize for 6.5.0Final to cast to interface type and not abstract class

Hibernate ORM
1

Hi,
we have a quite custom legacy solution migrating to Hiberate 6.5.0Final currently. So, maybe noone else will face this ClassCastException in CollectionEntry.postInitialize caused by casting to AbstractPersistentCollection in line

final SharedSessionContractImplementor session = ((AbstractPersistentCollection<?>)collection).getSession();

Why do we face this issue? Our custom collection class implements PersistentCollection but can not extend AbstractPersistentCollection.

Basically a possible solution to overcome this ClassCastException and having a cleaner casting to the interface type instead of casting to an abstract class can be achieved by extending PersistentCollection by a default method:

  default SharedSessionContractImplementor getSession() {
    return null;
  }

So the cast to the abstract class can be replaced by casting to the interface type PersistentCollection:

final SharedSessionContractImplementor session = ((PersistentCollection<?>)collection).getSession();

Happy to hear from you if this might be considered as an improvement.

2

This definitely looks like a bug. Would you mind creating a Jira issue?

I suspect @gavinking , who introduced the cast, will want to have a look.

EDIT: To clarify, your solution may be fine, and if so it’d be great if you could also send a PR, but I suspect we might want to plan for forcing PersistentCollection implementors to implement getSession in the future, which requires additional planning.

3

Agree, not having any casting at all would be the best solution. To send a PR is unfortunately not possible.

Creating a JIRA issue is in general no problem. Do you have a link to your JIRA?

4

https://hibernate.atlassian.net/browse/HHH

See also Come and join us! - Hibernate

5

[HHH-18067] - Hibernate JIRA created.