Spring provided a convenience property for "cacheRegionFactory" in the Hibernate 3.x and 4.x packages. The current support for Hibernate 5.x no longer provides this flexibility. This is quite unfortunate, as there are some scenarios where customization of the underlying cache infrastructure is desired, and injection of various Spring-managed dependencies is the natural approach.
Please note that the "hibernate.cache.region.factory_class" property is somewhat misleading: in addition to an implementation class, an actual object instance implementing org.hibernate.cache.spi.RegionFactory is equally valid: please see org.hibernate.cache.internal.RegionFactoryInitiator#initiateService.
At the moment we are using Hibernate 5.1.x, and I have not verified that the approach described below is equally applicable to 5.0.x/5.1.x/5.2.x/5.3.x APIs.
That said, the current workaround I am using is to subclass the hibernate5 LocalSessionFactoryBean as follows:
I've added a corresponding setCacheRegionFactory setter to LocalSessionFactoryBean as well as LocalSessionFactoryBuilder, going nicely with other recent additions such as setIntegrators and setBeanContainer. I prefer keeping this 5.1 only since there are quite a few related additions in that release, and there are easy enough workarounds for the time being.