Fix Spring-ORM SpringBeanContainer::getBeanClass returns proxy-class instead of target-class

[lbsekr]

Problem
Since Hibernate ORM 7.2.x, ManagedBeanRegistryImpl enforces that the class returned by ContainedBean::getBeanClass must be identical to the requested bean type.
Spring’s SpringContainedBean currently returns bean.getClass(), which for AOP-proxied beans is a synthetic CGLIB subclass rather than the user-defined type. This mismatch causes Hibernate to throw:

IllegalArgumentException: Bean is not of requested type

Root cause
SpringContainedBean misinterprets the contract of ContainedBean::getBeanClass(): it must return the original target class, not the runtime proxy class.

Solution
Use AopUtils.getTargetClass(bean) instead of bean.getClass() to defer the actual user-defined type of CGLIB/Java-proxy wrapper.

[lbsekr]

For context see this conversation with the maintainers of Hibernate-ORM
https://discourse.hibernate.org/t/managedbeanregistryimpl-getbean-in-7-2-0-throwing-exception/12057

[quaff]

@lbsekr I don't think it's a correct fix, I created #36116 including test case.

[lbsekr]

Yes, your fix looks more straightforward

[lbsekr]

I didn't take into account that ultimateTargetClass only defers from proxy-classes but does not retain abstract super type information.