postMethod.addRequestParameter("code", code);
postMethod.addRequestParameter("client_id", this.config.getKey());
postMethod.addRequestParameter("client_secret", this.config.getSecret());
postMethod.addRequestParameter("redirect_uri", httpRequest.getRequestURL().toString());
postMethod.addRequestParameter("grant_type", "authorization_code");
HttpConnection accessTokenConnection = postMethod.openConnection();
if (accessTokenConnection.getResponseCode() != HttpURLConnection.HTTP_OK) {
LOGGER.error("Access token request failed: %s", accessTokenConnection.getResponseMessage());
httpResponse.sendError(HttpServletResponse.SC_FORBIDDEN);
return null;