Request.Builder()
        .url(server.url("/"))
        .post(AsyncRequestBody())
        .build()
    val call = client.newCall(request)
    call.timeout()
      .timeout(500, TimeUnit.MILLISECONDS) // Long enough for the first TLS handshake.
    call.execute().use { response ->
      val requestBody = (call.request().body as AsyncRequestBody?)!!.takeSink()
      val responseBody = response.body.source()