public function setParentId($parentId)
    {
        $parentId = (int) $parentId;

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


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

        $this->parentId = $parentId;

        return $this;
    }