CDavAccount::getAddressbookModificationLabel

static function getAddressbookModificationLabel($collectionId)
{
	list($siteId) = $collectionId;

	$arFilter = self::GetAddressbookExtranetUserFilter($siteId);

	if (!empty($arFilter['XML_ID']))
		unset($arFilter['XML_ID']);

	$dbUsers = BitrixMainUserTable::getList(array(
		'filter' => $arFilter,
		'select' => array('TIMESTAMP_X'),
		'order' => array(
			'TIMESTAMP_X' => 'desc'
		),
		'limit' => 1
	));
	if ($arUser = $dbUsers->fetch())
		return $arUser["TIMESTAMP_X"];
	return "";
}