code: KeyFactory newNativeKeyFactory() {
      KeyFactory keyFactory = datastore.newKeyFactory();
      String namespace = Tenant.getNamespace();
      if (namespace != null) {
        keyFactory.setNamespace(namespace);
      }
      return keyFactory;
    }
docs: Creates and returns a new native KeyFactory. If a namespace was specified using {@link Tenant},
  the returned KeyFactory will have the specified namespace.
  
  @return a {@link KeyFactory}