.assertHeader("Donut", "b")
      .assertRequestHeader("Accept-Language", "en-US")
      .assertRequestHeader("Accept-Charset", "UTF-8")
      .assertRequestHeader("If-None-Match", "v1") // If-None-Match in the validation request.
      .assertSentRequestAtMillis(request2SentAt, request2ReceivedAt)
      .assertReceivedResponseAtMillis(request2SentAt, request2ReceivedAt)
  }

  @Test
  fun conditionalCacheHit_Async() {