synchronized (PROTOCOL_HANDLERS) {
            URLStreamHandler handler = (URLStreamHandler) PROTOCOL_HANDLERS.get(protocol);
            if (handler != null) {
                return handler;
            }
            if (factory != null) {
                handler = factory.createURLStreamHandler(protocol);
            }

    try {
      // SSLSocket.getApplicationProtocol returns "" if application protocols values will not
      // be used. Observed if you didn't specify SSLParameters.setApplicationProtocols
      when (val protocol = sslSocket.applicationProtocol) {
        null, "" -> null
        else -> protocol
      }
    } catch (e: UnsupportedOperationException) {

      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)
    }

        final String value = System.getProperty("java.protocol.handler.pkgs");
        if (StringUtil.isEmpty(value)) {
            buf.append("org.codelibs.fess.net.protocol");
        } else if (!value.contains("org.codelibs.fess.net.protocol")) {
            buf.append("|org.codelibs.fess.net.protocol");
        }
        if (buf.length() > 0) {
            System.setProperty("java.protocol.handler.pkgs", buf.toString());
        }
    }

    }

    /**
     * Get the protocol of the proxy server.
     *
     * @return the protocol of the proxy server
     */
    public String getProtocol() {
        return protocol;
    }

    /**
     * @param protocol the protocol of the proxy server like <i>SOCKSv4</i>
     */
    public void setProtocol(String protocol) {
        this.protocol = protocol;
    }

  }

  fun setUp(protocol: Protocol) {
    this.protocol = protocol
    platform.assumeNotOpenJSSE()
    if (protocol === Protocol.HTTP_2) {
      platform.assumeHttp2Support()
      server.useHttps(handshakeCertificates.sslSocketFactory())
      client =
        clientTestRule
          .newClientBuilder()
          .protocols(listOf(Protocol.HTTP_2, Protocol.HTTP_1_1))
          .sslSocketFactory(

        // Pick the first known protocol the peer advertises.
        for (i in 0..peerProtocols.size) {
          val protocol = peerProtocols[i] as String
          if (protocol in protocols) {
            selected = protocol
            return selected
          }
        }
        selected = protocols[0] // On no intersection, try peer's first protocol.
        return selected

          .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,

    } 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 {

        val sslSocket = doSsl(socket)
        val protocolString = Platform.get().getSelectedProtocol(sslSocket)
        val protocol = if (protocolString != null) get(protocolString) else null
        if (protocol != Protocol.HTTP_2) {
          throw ProtocolException("Protocol $protocol unsupported")
        }
        val connection =
          Http2Connection
            .Builder(false, TaskRunner.INSTANCE)