if(responseJSON.has("error")) {
throw new IllegalStateException();
}
String idToken = responseJSON.getString("id_token");
GoogleIdToken userIdToken = GoogleIdToken.parse(new JacksonFactory(), idToken);
GoogleIdToken.Payload googlePayload = userIdToken.getPayload();
String userId = googlePayload.getSubject();
if(googlePayload.getIssuer().equals("accounts.google.com")
&& googlePayload.getAudience().equals(this.clientId)) {