public function decline($account, $repo, $id, $params = array())
    {
        if (false === array_key_exists('message', $params)) {
            $params['message'] = '';
        }

        return $this->getClient()->setApiVersion('2.0')->post(
            sprintf('repositories/%s/%s/pullrequests/%d/decline', $account, $repo, $id),
            json_encode($params),
            array('Content-Type' => 'application/json')
        );
    }