public function getAssignment($roleName, $userId)
    {
        return isset($this->assignments[$userId][$roleName]) ? $this->assignments[$userId][$roleName] : null;
    }
public function getAssignment($roleName, $userId)
    {
        return isset($this->assignments[$userId][$roleName]) ? $this->assignments[$userId][$roleName] : null;
    }
{@inheritdoc}