* 2
     * Accept-Language: fr-CA
     * Accept-Charset: UTF-8
     * HTTP/1.1 200 OK
     * 3
     * Content-Type: image/png
     * Content-Length: 100
     * Cache-Control: max-age=600
     * ```
     *
     * A typical HTTPS file looks like this:
     *
     * ```
     * https://google.com/foo
     * GET
     * 2
     * Accept-Language: fr-CA
     * Accept-Charset: UTF-8

      Request.Builder()
        .url(url)
        .header("Accept-Language", "fr-CA")
        .build()
    val response1 = client.newCall(request).execute()
    assertThat(response1.body.string()).isEqualTo("A")
    val request1 =
      Request.Builder()
        .url(url)
        .header("Accept-Language", "fr-CA")
        .build()
    val response2 = client.newCall(request1).execute()

        .cache(cache)
        .build()

    // Store a response in the cache.
    val url = server.url("/")
    val request1SentAt = System.currentTimeMillis()
    executeSynchronously("/", "Accept-Language", "fr-CA", "Accept-Charset", "UTF-8")
      .assertCode(200)
      .assertBody("A")
    val request1ReceivedAt = System.currentTimeMillis()
    assertThat(server.takeRequest().headers["If-None-Match"]).isNull()

   *
   * If [routes] is non-null these are the resolved routes (ie. IP addresses) for the connection.
   * This is used to coalesce related domains to the same HTTP/2 connection, such as `square.com`
   * and `square.ca`.
   */
  fun callAcquirePooledConnection(
    doExtensiveHealthChecks: Boolean,
    address: Address,
    connectionUser: ConnectionUser,
    routes: List<Route>?,
    requireMultiplexed: Boolean,