Qualified `EntityManager`/`EntityManagerFactory` injection (aligned with Jakarta Persistence 3.2)

[hantsy]

It is great that Spring 6.2 adds initial Jakarta Persistence 3.2 support.

Jakarta Persistence 3.2 brings CDI Inject support for EntityManager and EntityManagerFactory.

Spring should align with this change and add Inject/Autowired support for EntityManager and EntityManagerFactory

@Inject @BookstoreDB
EntityManager bookstoreEM;

@Inject @CustomersDB
EntityManager customersEM;

The @BookstoreDB and CustomersDB are meta-annotations with @Qulifier to identify different persistence unit/datasource. And allow developers to create the EMF factory bean with these qualifiers(1) or properties(2,3) to specify it.

@BookstoreDB // 1
@Bean 
public LocalContainerEntityManagerFactoryBean ...(){

    emf.setQulifierNames(array of string) // 2
    emf.setQulifierClasses(array of classes) // 3
}

By default, only one db data source, all qualifiers can be ignored.