src/ReactFactory.php
public static function buildHttpClient(
        LoopInterface $loop,
        $connector = null
    ) {
        if (class_exists(HttpClientFactory::class)) {
            // if HttpClientFactory class exists, use old behavior for backwards compatibility
            return static::buildHttpClient04($loop, $connector);
        } else {
            return static::buildHttpClient05($loop, $connector);
        }
    }
public static function buildHttpClient(
        LoopInterface $loop,
        $connector = null
    ) {
        if (class_exists(HttpClientFactory::class)) {
            // if HttpClientFactory class exists, use old behavior for backwards compatibility
            return static::buildHttpClient04($loop, $connector);
        } else {
            return static::buildHttpClient05($loop, $connector);
        }
    }
Build a React Http Client.

@param LoopInterface                       $loop
@param ConnectorInterface|DnsResolver|null $connector Only pass this argument if you need to customize DNS
behaviour. With react http client v0.5, pass a connector,
with v0.4 this must be a DnsResolver.

@return HttpClient