protected function get_options() {
        global $CFG;
        $options = parent::get_options();
        $options['file'] = $CFG->admin.'/webservice/lib.php'; //need to be set, otherwise
                                                        // the /user/selector/search.php
                                                        //will fail to find this user_selector class
        $options['serviceid'] = $this->serviceid;
        $options['displayallowedusers'] = $this->displayallowedusers;
        return $options;
    }