public function setUserId($userId)
    {
        $userId = (int) $userId;

        if ($this->userId < 0) {
            throw new \UnderflowException('Value of "userId" must be greater than 0');
        }


        if ($this->exists() && $this->userId !== $userId) {
            $this->updated['userId'] = true;
        }

        $this->userId = $userId;

        return $this;
    }