val response = client.newCall(request).execute()

    response.use {
      assertEquals(200, response.code)
      assertEquals(TlsVersion.TLS_1_3, response.handshake?.tlsVersion)
      assertEquals(Protocol.HTTP_2, response.protocol)

      assertThat(response.exchangeAccessor!!.connectionAccessor.socket())
        .isInstanceOf<SSLSocketImpl>()
    }
  }

  @Test
  fun testSupportedProtocols() {

     *
     * @param protocol
     *            The URL protocol. Must not be {@literal null} or empty.
     * @param factory
     *            The {@link Traverser} factory for the protocol. Must not be {@literal null}.
     */
    public static void addTraverserFactory(final String protocol, final TraverserFactory factory) {
        assertArgumentNotEmpty("protocol", protocol);

      super.configureTlsExtensions(sslSocket, hostname, protocols)
    }
  }

  override fun getSelectedProtocol(sslSocket: SSLSocket): String? =
    if (sslSocket is BCSSLSocket) {
      when (val protocol = (sslSocket as BCSSLSocket).applicationProtocol) {
        // Handles both un-configured and none selected.
        null, "" -> null
        else -> protocol
      }
    } else {
      super.getSelectedProtocol(sslSocket)
    }

    } else {
      super.configureTlsExtensions(sslSocket, hostname, protocols)
    }
  }

  override fun getSelectedProtocol(sslSocket: SSLSocket): String? =
    if (sslSocket is org.openjsse.javax.net.ssl.SSLSocket) {
      when (val protocol = sslSocket.applicationProtocol) {
        // Handles both un-configured and none selected.
        null, "" -> null
        else -> protocol
      }
    } else {

          .build()
      }
    assertThat(e).hasMessage("expected a null request body with 'Connection: upgrade'")
  }

  private fun enableTls(vararg protocols: Protocol) {
    client =
      client
        .newBuilder()
        .protocols(protocols.toList())
        .sslSocketFactory(
          handshakeCertificates.sslSocketFactory(),
          handshakeCertificates.trustManager,

  override fun configureTlsExtensions(
    sslSocket: SSLSocket,
    hostname: String?,
    protocols: List<Protocol>,
  ) {
    getDelegate(sslSocket)?.configureTlsExtensions(sslSocket, hostname, protocols)
  }

  override fun getSelectedProtocol(sslSocket: SSLSocket): String? = getDelegate(sslSocket)?.getSelectedProtocol(sslSocket)

        .url("https://google.com/robots.txt")
        .build();
    try (Response response = client.newCall(request).execute()) {
      assertEquals(200, response.code());
      assertEquals(Protocol.HTTP_2, response.protocol());
    }
  }

            .url(url)
            .build();
    try (Response response = client.newCall(request).execute()) {
      assertTrue(response.code() == 200 || response.code() == 404);
      assertEquals(Protocol.HTTP_2, response.protocol());

      for (Certificate c: response.handshake().peerCertificates()) {
        X509Certificate x = (X509Certificate) c;
        System.out.println(x.getSubjectDN());
      }
    }
  }

   * HTTPS.
   */
  fun handshake(): Handshake?

  /**
   * Returns the protocol negotiated by this connection, or [Protocol.HTTP_1_1] if no protocol
   * has been negotiated. This method returns [Protocol.HTTP_1_1] even if the remote peer is using
   * [Protocol.HTTP_1_0].
   */
  fun protocol(): Protocol

    }

    /**
     * Adds a new file protocol to the supported protocols list.
     * If the protocol already exists, it will not be added again.
     *
     * @param protocol the protocol name to add (without colon suffix)
     */
    public void addFileProtocol(final String protocol) {
        final String prefix = protocol + ":";