protected function ensureSchema($arr_entities)
    {
        foreach($arr_entities as $obj_gds_entity) {
            if($obj_gds_entity instanceof Entity) {
                if (null === $obj_gds_entity->getKind()) {
                    $obj_gds_entity->setSchema($this->obj_schema);
                }
            } else {
                throw new \InvalidArgumentException('You gave me something other than GDS\Entity objects.. not gonna fly!');
            }
        }
    }