private function extractGuzzleConfig($config)
    {
        foreach (ConfigUtils::$GUZZLE_CONFIG_KEYS as $guzzleOption) {
            if (array_key_exists($guzzleOption, $config)) {
                $this->guzzleConfig[$guzzleOption] = $config[$guzzleOption];
                unset($config[$guzzleOption]);
            }
        }

        return $config;
    }