GroupStepper::getFileIds

private function getFileIds(?Folder $rootFolder): array
{
	$fileIds = [];

	$securityContext = Driver::getInstance()->getFakeSecurityContext();

	$params = ["select" => ["*", "HAS_SUBFOLDERS"]];
	foreach ($rootFolder->getChildren($securityContext, $params) as $child)
	{
		if ($child instanceof Folder)
		{
			if ($child->getChildren($securityContext))
			{
				$fileIds = array_merge($fileIds, $this->getFileIds($child));
			}
		}
		elseif ($child instanceof File)
		{
			$fileIds[] = $child->getId();
		}
	}

	return $fileIds;
}