This service interface offers JPA clients the ability to create instances of
EntityManagerFactory for a given named persistence unit. A service instance
will be created for each named persistence unit and can be filtered by
comparing the value of the osgi.unit.name property containing the persistence
This service is used specifically when the caller wants to pass in
factory-scoped properties as arguments. If no properties are being used in
the creation of the EntityManagerFactory then the basic EntityManagerFactory
service should be used.