src/services/SitemapService.php
private function _getUpdated (Element $type, $id)
	{
		/** @var EntryQuery|CategoryQuery $criteria */
		$criteria = $type::find();

		$this->_setCriteriaIdByType($criteria, $type, $id);

		$criteria->limit = 1;

		$element = $criteria->one();
		return $element ? $element->dateUpdated->format('c') : '';
	}
private function _getUpdated (Element $type, $id)
	{
		/** @var EntryQuery|CategoryQuery $criteria */
		$criteria = $type::find();

		$this->_setCriteriaIdByType($criteria, $type, $id);

		$criteria->limit = 1;

		$element = $criteria->one();
		return $element ? $element->dateUpdated->format('c') : '';
	}
Get's the latest updated element date for the given element type and
group / section ID

@param Element $type - The Element Type
@param int     $id - The section or group ID

@return \DateTime|string