protected function allUsers()
    {
        $directory = Google::make('directory');
        $pageToken = null;
        $users = [];
        do {
            try {
                $r = $directory->users->listUsers([
                    'domain' => config('users.google_apps_domain'),
                    'maxResults' => config('users.google_apps_users_maxResults'),
                    'pageToken' => $pageToken
                ]);
                $pageToken = $r->nextPageToken;
                $users = array_merge($users, $r->users);
            } catch (\Exception $e) {
                return json_decode($e->getMessage());
            }
        } while ($pageToken);
        return $users;
    }