.cache(cache)
        .build()
    val request1 = Request(server.url("/"))
    client.newCall(request1).enqueue(callback)
    callback.await(request1.url).assertCode(200).assertBody("A")
    assertThat(server.takeRequest().headers["If-None-Match"]).isNull()
    val request2 = Request(server.url("/"))
    client.newCall(request2).enqueue(callback)
    callback.await(request2.url).assertCode(200).assertBody("A")