private function getOrCreateGroup(string $namespace): Group {
		$group = $this->em->find(Group::getClass(), $namespace);

		if (null !== $group) {
			return $group;
		}

		$group = new Group($namespace);
		$t = $this->tm->createTransaction();
		$this->em->persist($group);
		$t->commit();
		return $group;
	}