protected function __before(ServerRequestInterface $request, array $arguments)
    {
        $type_id_variable = $this->getTypeIdVariable();

        if (array_key_exists($type_id_variable, $arguments)) {
            $this->active_object = empty($arguments[$type_id_variable]) ? null : $this->pool->getById($this->getTypeClassName(), $arguments[$type_id_variable]);

            if (empty($this->active_object)) {
                return new NotFoundStatusResponse();
            }
        }

        return null;
    }