HTTP_1_0.protocol -> HTTP_1_0
        HTTP_1_1.protocol -> HTTP_1_1
        H2_PRIOR_KNOWLEDGE.protocol -> H2_PRIOR_KNOWLEDGE
        HTTP_2.protocol -> HTTP_2
        SPDY_3.protocol -> SPDY_3
        QUIC.protocol -> QUIC
        else -> {
          // Support HTTP3 draft like h3-29
          if (protocol.startsWith(HTTP_3.protocol)) HTTP_3 else throw IOException("Unexpected protocol: $protocol")
        }

     * Returns the concatenation of 8-bit, length prefixed protocol names.
     * http://tools.ietf.org/html/draft-agl-tls-nextprotoneg-04#page-4
     */
    fun concatLengthPrefixed(protocols: List<Protocol>): ByteArray {
      val result = Buffer()
      for (protocol in alpnProtocolNames(protocols)) {
        result.writeByte(protocol.length)
        result.writeUtf8(protocol)
      }
      return result.readByteArray()
    }

 */
package okhttp3.internal.http

import okhttp3.OkHttpClient
import okhttp3.Protocol
import okhttp3.Request

object ExternalHttp2Example {
  @JvmStatic
  fun main(args: Array<String>) {
    val client =
      OkHttpClient.Builder()
        .protocols(listOf(Protocol.HTTP_2, Protocol.HTTP_1_1))
        .build()
    val call =
      client.newCall(
        Request.Builder()

      assertThat(response.body.string()).isEqualTo("healthy")
    }
  }

  private fun enableProtocol(protocol: Protocol) {
    enableTls()
    client =
      client.newBuilder()
        .protocols(listOf(protocol, Protocol.HTTP_1_1))
        .build()
    server.protocols = client.protocols
  }

  private fun enableTls() {
    client =
      client.newBuilder()
        .sslSocketFactory(

    val s = sslSocket as BCSSLSocket

    return when (val protocol = s.applicationProtocol) {
      null, "" -> null
      else -> protocol
    }
  }

  override fun configureTlsExtensions(
    sslSocket: SSLSocket,
    hostname: String?,
    protocols: List<Protocol>,
  ) {
    // No TLS extensions if the socket class is custom.
    if (matchesSocket(sslSocket)) {

    }
  }

  override fun protocol(): Protocol = protocol!!

  override fun toString(): String {
    return "Connection{${route.address.url.host}:${route.address.url.port}," +
      " proxy=${route.proxy}" +
      " hostAddress=${route.socketAddress}" +
      " cipherSuite=${handshake?.cipherSuite ?: "none"}" +
      " protocol=$protocol}"
  }

  companion object {

    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() {

            .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());
      }
    }
  }

    platform.assumeHttp2Support()
    setsNegotiatedProtocolHeader(Protocol.HTTP_2)
  }

  private fun setsNegotiatedProtocolHeader(protocol: Protocol) {
    enableProtocol(protocol)
    server.enqueue(
      MockResponse(body = "A"),
    )
    client =
      client.newBuilder()
        .protocols(Arrays.asList(protocol, Protocol.HTTP_1_1))
        .build()

 *   override fun intercept(chain: Interceptor.Chain): Response {
 *     if (myConfig.isInvalid()) {
 *       return Response.Builder()
 *           .request(chain.request())
 *           .protocol(Protocol.HTTP_1_1)
 *           .code(400)
 *           .message("client config invalid")
 *           .body("client config invalid".toResponseBody(null))
 *           .build()
 *     }
 *