val t0 = System.currentTimeMillis()
    val response1 = get(server.url("/a"))
    assertThat(response1.body.string()).isEqualTo("A")
    assertThat(response1.header("Allow")).isNull()
    assertThat((response1.receivedResponseAtMillis - t0).toDouble()).isCloseTo(0.0, 250.0)

    // A conditional cache hit updates the cache.
    Thread.sleep(500) // Make sure t0 and t1 are distinct.
    val t1 = System.currentTimeMillis()