I'm implementing JPAInjectionServices.

When working with EntityManager references, should I:

• create the EntityManager in the ResourceReference#getInstance() method (like Hammock does, and, from a search on Github, like many others do—IMHO this seems wrong)
• create the EntityManager in a ResourceReferenceFactory#createResource() implementation and return a SimpleResourceReference holding the result (IMHO this seems like the proper way to do it, but it seems no one else—at least on Github—does it this way)

…?

In other words, should the ResourceReference#getInstance() method implementation be a factory, returning a new EntityManager instance every time it is invoked, or should it be a "holder", returning a single instance every time it is invoked?

The javadocs for ResourceReference#getInstance() and ResourceReferenceFactory#createResource() do not help here.

Best,

Laird