private function getWorkspaceUsersIds(Workspace $workspace)
    {
        // Select all user(s) belonging to the target workspace (manager and collaborators)...
        $selectUsersIds = 'SELECT DISTINCT cur.user_id FROM claro_user_role cur JOIN claro_role cr ON cr.id = cur.role_id  WHERE cr.workspace_id = :wid';
        $idStmt = $this->em->getConnection()->prepare($selectUsersIds);
        $idStmt->bindValue('wid', $workspace->getId());
        $idStmt->execute();
        $idResults = $idStmt->fetchAll();
        foreach ($idResults as $result) {
            $ids[] = $result['user_id'];
        }

        return $ids;
    }