@Override
    public HttpResponse loginFailed(ServiceRequestContext ctx, AggregatedHttpRequest req,
                                    @Nullable MessageContext<Response> message, Throwable cause) {
        return HttpResponse.of(HttpStatus.UNAUTHORIZED, MediaType.HTML_UTF_8,
                               "<html><body>Login failed.</body></html>");
    }
Invoked when a single sign-on request is rejected from the identity provider.
examples/saml-service-provider/src/main/java/example/armeria/server/saml/sp/MyAuthHandler.java