.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());
      }
    }
  }

    server.setProtocols(Collections.singletonList(Protocol.H2_PRIOR_KNOWLEDGE));
    server.enqueue(new MockResponse().setBody("hello"));
    server.start();

    OkHttpClient client = new OkHttpClient.Builder()
        .socketFactory(new UnixDomainSocketFactory(socketFile))
        .protocols(Collections.singletonList(Protocol.H2_PRIOR_KNOWLEDGE))
        .build();

    Request request = new Request.Builder()

    }

    @Override public void connectEnd(
        Call call, InetSocketAddress inetSocketAddress, Proxy proxy, Protocol protocol) {
      printEvent("connectEnd");
    }

    @Override public void connectFailed(Call call, InetSocketAddress inetSocketAddress, Proxy proxy,
        Protocol protocol, IOException ioe) {
      printEvent("connectFailed");
    }

    }

    @Override public void connectEnd(
        Call call, InetSocketAddress inetSocketAddress, Proxy proxy, Protocol protocol) {
      printEvent("connectEnd");
    }

    @Override public void connectFailed(Call call, InetSocketAddress inetSocketAddress, Proxy proxy,
        Protocol protocol, IOException ioe) {
      printEvent("connectFailed");
    }

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

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

      String responseSource = response.networkResponse() != null ? ("(network: "
          + response.networkResponse().code()
          + " over "
          + response.protocol()
          + ")") : "(cache)";
      int responseCode = response.code();

      System.out.printf("%03d: %s %s%n", responseCode, url, responseSource);

      String contentType = response.header("Content-Type");