* if (forceCacheResponse.code() != 504) {
 *   // The resource was cached! Show it.
 * } else {
 *   // The resource was not cached.
 * }
 * ```
 *
 * This technique works even better in situations where a stale response is better than no response.
 * To permit stale cached responses, use the `max-stale` directive with the maximum staleness in
 * seconds:
 *
 * ```java

    val tlsFallbackScsv = "TLS_FALLBACK_SCSV"
    val supportedCiphers = listOf(*handshakeCertificates.sslSocketFactory().supportedCipherSuites)
    if (!supportedCiphers.contains(tlsFallbackScsv)) {
      // This only works if the client socket supports TLS_FALLBACK_SCSV.
      return
    }
    server.useHttps(handshakeCertificates.sslSocketFactory())
    server.enqueue(MockResponse(socketPolicy = FailHandshake))

    val call1 = client.newCall(Request(server.url("/")))
    val response = call1.execute()
    call1.cancel()

    // That connection is pooled, and it works.
    assertThat(client.connectionPool.connectionCount()).isEqualTo(1)
    val call2 = client.newCall(Request(server.url("/")))
    val response2 = call2.execute()
    assertThat(response2.body.string()).isEqualTo("def")

 *  Fix: Don't call `toDuration()` which isn't available in kotlin-stdlib 1.4.


## Version 5.0.0-alpha.8

_2022-06-08_

 *  Fix: Change how `H2_PRIOR_KNOWLEDGE` works with HTTP proxies. Previously OkHttp assumed the
    proxy itself was a prior knowledge HTTP/2 server. With this update, OkHttp attempts a `CONNECT`

     *    public List<X509Certificate> checkServerTrusted(
     *        X509Certificate[] chain, String authType, String host) throws CertificateException {
     *    }
     * ```
     *
     * This method works like [X509TrustManager.checkServerTrusted] but it receives the hostname of
     * the server as an extra parameter. Regardless of what checks this method performs, OkHttp will

 *
 * ## Protocol vs Scheme
 *
 * Despite its name, [java.net.URL.getProtocol] returns the [scheme][java.net.URI.getScheme] (http,
 * https, etc.) of the URL, not the protocol (http/1.1, spdy/3.1, etc.). OkHttp uses the word
 * *protocol* to identify how HTTP messages are framed.
 *
 * [ietf_alpn]: http://tools.ietf.org/html/draft-ietf-tls-applayerprotoneg
 */
enum class Protocol(private val protocol: String) {
  /**