JiraRestApi\Issue\IssueField::setParentKeyOrId PHP Method

    public function setParentKeyOrId($keyOrId)
    {
        if (is_numeric($keyOrId)) {
            $this->parent['id'] = $keyOrId;
        } elseif (is_string($keyOrId)) {
            $this->parent['key'] = $keyOrId;
        }
    }