public static function get_identity_providers($authsequence) {
        global $SESSION;

        $identityproviders = [];
        foreach ($authsequence as $authname) {
            $authplugin = get_auth_plugin($authname);
            $wantsurl = (isset($SESSION->wantsurl)) ? $SESSION->wantsurl : '';
            $identityproviders = array_merge($identityproviders, $authplugin->loginpage_idp_list($wantsurl));
        }
        return $identityproviders;
    }