Introduce interface cache for proxied EntityManager and Query types

[mp911de]

We now reuse interfaces for EntityManager and Query classes that are proxied through ExtendedEntityManagerCreator and SharedEntityManagerCreator.

These caches prevent excessive object allocations through ClassUtils.getAllInterfacesForClass(…) and ClassUtils.getAllInterfacesForClassAsSet(…).

Example benchmark:

@State(Scope.Benchmark)
@Fork(value = 1)
public class EmBenchmark {

	EntityManager em;

	@Setup
	public void prepare() {

		EntityManagerFactory emf = …;
		em = SharedEntityManagerCreator.createSharedEntityManager(emf, null);
	}

	@Benchmark
	public void measure(Blackhole voodoo) {
		voodoo.consume(em.createQuery("SELECT p FROM Person p"));
	}
}

Measurement:

Before:
Benchmark                Mode  Cnt       Score        Error  Units
EmBenchmark.measureJpa  thrpt    5  650483,423  ± 29876,924  ops/s

After:
Benchmark                Mode  Cnt       Score        Error  Units
EmBenchmark.measureJpa  thrpt    5  734358,219  ± 74288,478  ops/s