Request request = new Request.Builder()
            .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;

      int responseCode = response.code();

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

      String contentType = response.header("Content-Type");
      if (responseCode != 200 || contentType == null) {
        return;
      }

      MediaType mediaType = MediaType.parse(contentType);
      if (mediaType == null || !mediaType.subtype().equalsIgnoreCase("html")) {
        return;
      }