code: public void deleteByKey(List<DatastoreKey> keys) {
      try {
        Key[] nativeKeys = new Key[keys.size()];
        for (int i = 0; i < keys.size(); i++) {
          nativeKeys[i] = keys.get(i).nativeKey();
        }
        nativeWriter.delete(nativeKeys);
      } catch (DatastoreException exp) {
        throw DatastoreUtils.wrap(exp);
      }
    }
docs: Deletes the entities having the given keys.
  
  @param keys
  the entities' keys
  @throws EntityManagerException
  if any error occurs while deleting.