public function getCustomServiceAccountList()
    {
        $url    = sprintf(self::CS_ACCOUNT_LISTS_URL, $this->getAccessTokenString());
        $client = $this->getHttpClient();
        $client->setUrl($url);
        $client->setHeaderArray(['Content-Type: application/json']);

        if (!$client->exec()) {
            throw new Exception("call get custom service account list fail");
        }

        $result = json_decode($client->getResponse(), true);
        if (isset($result['errcode'])) {
            throw new Exception("error response for get custom service account list");
        }

        return $result;
    }