public function setHttpClient($httpClient) {
    if (is_null($httpClient)) {
      $httpClient = new Curl;
      $threeScaleVersion = new ThreeScaleVersion();

      $version = $threeScaleVersion->getVersion();

      $httpClient->options['CURLOPT_FOLLOWLOCATION'] = false;
      $httpClient->headers['X-3scale-User-Agent'] = 'plugin-php-v'. $version;
    }

    $this->httpClient = $httpClient;
  }