SectionTable::onUpdate

static function onUpdate(Event $event)
{
	/** @var EO_Section $section */
	$section = $event->getParameter('object');

	// save old fields
	$oldValues = CIBlockSection::GetList([], ["ID" => $section->getId(), "CHECK_PERMISSIONS" => "N"]);
	$section->customData->set('RECOUNT_TREE_OLD_VALUES', $oldValues);
}