code: public <E> List<E> loadByKey(Class<E> entityClass, List<DatastoreKey> keys) {
      Key[] nativeKeys = DatastoreUtils.toNativeKeys(keys);
      return fetch(entityClass, nativeKeys);
    }
docs: Retrieves and returns the entities for the given keys.
  
  @param entityClass
  the expected result type
  @param keys
  the entity keys
  @return the entities for the given keys. If one or more requested keys do not exist in the
  Cloud Datastore, the corresponding item in the returned list be <code>null</code>.
  
  @throws EntityManagerException
  if any error occurs while accessing the Datastore.