V2AuthRequest.ChallengeResponse challengeResponse = ChallengeResponses.respondToRegistrationChallenge(
certificateAndKey, registerResponse.challenge);
registerRequest.challengeResponse = challengeResponse;
registerResponse = client.register(registerRequest, certificateAndKey);
if (Strings.isNullOrEmpty(registerResponse.userId)) {
throw new RestClientException("Unable to register (invalid response)");
}
}