Tpl::findActivityUsagesRecursive

private function findActivityUsagesRecursive(CBPActivity $activity, CollectionUsages $usages)
{
	$sources = $activity->collectUsages();
	$usages->addOwnerSources($activity->GetName(), $sources);

	$children = $activity->CollectNestedActivities();
	if (is_array($children))
	{
		foreach ($children as $child)
		{
			$this->findActivityUsagesRecursive($child, $usages);
		}
	}
	return $usages;
}