code: 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;
  	}
docs: Gets group if exists.
  If Category does not exist a new one is created.
  
  @param string $namespace
  @return Group