override fun contentType(): MediaType = "text/plain".toMediaType()

        override fun writeTo(sink: BufferedSink) {
          sink.writeUtf8("abc")
          sink.timeout().deadline(5, TimeUnit.SECONDS)
        }
      }
    val request1 =
      Request.Builder()
        .url(server.url("/"))
        .method("POST", requestBody1)
        .build()

    //      last modified: 105 seconds ago
    //             served:   5 seconds ago
    //   default lifetime: (105 - 5) / 10 = 10 seconds
    //            expires:  10 seconds from served date = 5 seconds from now
    server.enqueue(
      MockResponse.Builder()
        .addHeader("Last-Modified: " + formatDate(-105, TimeUnit.SECONDS))
        .addHeader("Date: " + formatDate(-5, TimeUnit.SECONDS))