public function getCommonLeaders($actor)
    {
        if (!isset($this->__common_leaders)) {
            $ids = array_intersect($this->leaderIds->toArray(), $actor->leaderIds->toArray());
            $ids[] = -1;
            $query = $this->getService('repos:actors.actor')->getQuery()->where('id', 'IN', $ids);

            $this->__common_leaders = $query->toEntitySet();
        }

        return $this->__common_leaders;
    }