class U2F {

    public RegisterRequestData startRegistration(String appId, Iterable<? extends DeviceRegistration> devices) throws U2fBadConfigurationException {
        if(validateAppId) {
            AppId.checkIsValid(appId);
        }
        return new RegisterRequestData(appId, devices, primitives, challengeGenerator);
    }

    public  U2F();
    private  U2F(boolean validateAppId);

}