*  **OkHttp now supports duplex calls over HTTP/2.** With normal HTTP calls the request must finish
    before the response starts. With duplex, request and response bodies are transmitted
    simultaneously. This can be used to implement interactive conversations within a single HTTP
    call.

    Create duplex calls by overriding the new `RequestBody.isDuplex()` method to return true.

    )
    val read = response1.body.source().read(ByteArray(8192))
    assertThat(read).isEqualTo(8192)

    // Make a second call that should transmit the response headers. The response body won't be
    // transmitted until the flow-control window is updated from the first request.
    val call2 = client.newCall(Request(server.url("/")))
    val response2 = call2.execute()
    assertThat(response2.code).isEqualTo(200)