function do_deleteSource()
 {
     $oSource =& $this->oValidator->validateAuthenticationSource($_REQUEST['source_id']);
     $aGroups = Group::getByAuthenticationSource($oSource);
     $aUsers = User::getByAuthenticationSource($oSource);
     if (empty($aUsers) && empty($aGroups)) {
         $oSource->delete();
         $this->successRedirectToMain(_kt("Authentication source deleted"));
     }
     $this->errorRedirectToMain(_kt("Authentication source is still in use, not deleted"));
 }