/**
  * Decode an HTTP Response.
  * @static
  * @throws ServiceException
  * @param HttpRequest $response The http response to be decoded.
  * @return mixed|null
  */
 public static function decodeHttpResponse($response)
 {
     $code = $response->getResponseHttpCode();
     $body = $response->getResponseBody();
     $decoded = null;
     if (intVal($code) >= 300) {
         $decoded = json_decode($body, true);
         $err = 'Error calling ' . $response->getRequestMethod() . ' ' . $response->getUrl();
         if ($decoded != null && isset($decoded['error']['message']) && isset($decoded['error']['code'])) {
             // if we're getting a json encoded error definition, use that instead of the raw response
             // body for improved readability
             $err .= ": ({$decoded['error']['code']}) {$decoded['error']['message']}";
         } else {
             $err .= ": ({$code}) {$body}";
         }
         throw new Google_ServiceException($err, $code, null, $decoded['error']['errors']);
     }
     // Only attempt to decode the response, if the response code wasn't (204) 'no content'
     if ($code != '204') {
         $decoded = json_decode($body, true);
         if ($decoded === null || $decoded === "") {
             throw new Google_ServiceException("Invalid json in service response: {$body}");
         }
     }
     return $decoded;
 }