/**
     * Extension header set by OkHttp specifying the timestamp when the cached HTTP response was
     * first received.
     */
    private var receivedResponseMillis = 0L

    /** Etag of the cached response. */
    private var etag: String? = null

    /** Age of the cached response. */
    private var ageSeconds = -1

    /**
     * Returns true if computeFreshnessLifetime used a heuristic. If we used a heuristic to serve a

    // Special case some of the weird HTTP Header names...
    ImmutableBiMap<String, String> specialCases =
        ImmutableBiMap.<String, String>builder()
            .put("CDN_LOOP", "CDN-Loop")
            .put("ETAG", "ETag")
            .put("SOURCE_MAP", "SourceMap")
            .put("SEC_CH_UA_WOW64", "Sec-CH-UA-WoW64")
            .put("SEC_WEBSOCKET_ACCEPT", "Sec-WebSocket-Accept")

    assertThat(invalidate.body.string()).isEqualTo("")
    assertThat(get(url).body.string()).isEqualTo("C")
  }

  @Test
  fun etag() {
    val conditionalRequest =
      assertConditionallyCached(
        MockResponse
          .Builder()
          .addHeader("ETag: v1")
          .build(),
      )
    assertThat(conditionalRequest.headers["If-None-Match"]).isEqualTo("v1")
  }

    enableCache()
    server.enqueue(
      MockResponse
        .Builder()
        .addHeader("ETag: v1")
        .body("abc")
        .build(),
    )
    server.enqueue(
      MockResponse
        .Builder()
        .code(HttpURLConnection.HTTP_OK)
        .addHeader("ETag: v2")
        .body("abd")
        .build(),
    )
    var call =
      client.newCall(

    call.cancel()
    assertFailsWith<IOException> {
      call.execute()
    }
    assertThat(server.requestCount).isEqualTo(0)
  }

  @Tag("Slowish")
  @Test
  fun cancelDuringHttpConnect() {
    cancelDuringConnect("http")
  }

  @Tag("Slowish")
  @Test
  fun cancelDuringHttpsConnect() {
    cancelDuringConnect("https")
  }

   *
   * @since 28.2
   */
  public static final String CROSS_ORIGIN_OPENER_POLICY = "Cross-Origin-Opener-Policy";

  /** The HTTP {@code ETag} header field name. */
  public static final String ETAG = "ETag";

  /** The HTTP {@code Expires} header field name. */
  public static final String EXPIRES = "Expires";

  /** The HTTP {@code Last-Modified} header field name. */

      Header("content-length", ""),
      Header("content-location", ""),
      Header("content-range", ""),
      Header("content-type", ""),
      Header("cookie", ""),
      Header("date", ""),
      Header("etag", ""),
      Header("expect", ""),
      Header("expires", ""),
      Header("from", ""),
      Header("host", ""),
      Header("if-match", ""),
      Header("if-modified-since", ""),

v.data)&&(f+=(At.test(f)?"&":"?")+v.data,delete v.data),!1===v.cache&&(f=f.replace(It,"$1"),o=(At.test(f)?"&":"?")+"_="+jt.guid+++o),v.url=f+o),v.ifModified&&(ce.lastModified[f]&&T.setRequestHeader("If-Modified-Since",ce.lastModified[f]),ce.etag[f]&&T.setRequestHeader("If-None-Match",ce.etag[f])),(v.data&&v.hasContent&&!1!==v.contentType||t.contentType)&&T.setRequestHeader("Content-Type",v.contentType),T.setRequestHeader("Accept",v.dataTypes[0]&&v.accepts[v.dataTypes[0]]?v.accepts[v.dataTypes[0]]+("*"!==v.dataTypes[0]?",...

v.data)&&(f+=(At.test(f)?"&":"?")+v.data,delete v.data),!1===v.cache&&(f=f.replace(It,"$1"),o=(At.test(f)?"&":"?")+"_="+jt.guid+++o),v.url=f+o),v.ifModified&&(ce.lastModified[f]&&T.setRequestHeader("If-Modified-Since",ce.lastModified[f]),ce.etag[f]&&T.setRequestHeader("If-None-Match",ce.etag[f])),(v.data&&v.hasContent&&!1!==v.contentType||t.contentType)&&T.setRequestHeader("Content-Type",v.contentType),T.setRequestHeader("Accept",v.dataTypes[0]&&v.accepts[v.dataTypes[0]]?v.accepts[v.dataTypes[0]]+("*"!==v.dataTypes[0]?",...

 *  Fix: Prefer TLSv1.2 where it is available. On certain older platforms it is necessary to opt-in
    to TLSv1.2.
 *  New: `Request.tag()` permits multiple tags. Use a `Class<?>` as a key to identify tags. Note
    that `tag()` now returns null if the request has no tag. Previously this would return the
    request itself.
 *  New: `Headers.Builder.addAll(Headers)`.
 *  New: `ResponseBody.create(MediaType, ByteString)`.