code: public Map<Key, Object> loadRelatedEntities(String... propertyName) {
  		EntityManager entityManager = EntityManagerFactory.getEntityManager();
  		Class<J> persistentClass = (Class<J>) query.getClassMetadata().getPersistentClass();
  		Set<Key> keys = Sets.newHashSet();
  		for (String p : propertyName) {
  			keys.addAll(Collections2.transform(data, new EntityToPropertyFunction(persistentClass, p)));
  		}
  		return entityManager.get(keys);
  	}
docs: Load the list of related entities.
  @param propertyName the name of the properties to be used as Key
  @return the list of retrieved entities