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")
        }

        // 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

      assertThat(acceptedHostName).isEqualTo(hostname)

      if (socketMode.tlsExtensionMode == STANDARD) {
        assertThat(response.protocol).isEqualTo(socketMode.protocol)
      } else {
        assertThat(response.protocol).isEqualTo(HTTP_1_1)
      }
    }
  }

  companion object {
    @Suppress("unused")
    @JvmStatic
    fun connectionTypes(): List<SocketMode> =

    assertThat(statusLine.protocol).isEqualTo(Protocol.HTTP_1_1)
    assertThat(statusLine.code).isEqualTo(code)
  }

  @Test
  fun emptyMessage() {
    val version = 1
    val code = 503
    val statusLine = parse("HTTP/1.$version $code ")
    assertThat(statusLine.message).isEqualTo("")
    assertThat(statusLine.protocol).isEqualTo(Protocol.HTTP_1_1)
    assertThat(statusLine.code).isEqualTo(code)
  }

     * 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()
    }

        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)

  override fun secureConnectEnd(handshake: Handshake?) {
    eventListener.secureConnectEnd(call, handshake)
  }

  override fun callConnectEnd(
    route: Route,
    protocol: Protocol?,
  ) {
    eventListener.connectEnd(call, route.socketAddress, route.proxy, protocol)
  }

  override fun connectionConnectEnd(
    connection: Connection,
    route: Route,
  ) {
    poolConnectionListener.connectEnd(connection, route, call)

 */
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(Protocol.SPDY_3.toString()).isEqualTo("spdy/3.1")
    assertThat(Protocol.HTTP_2.toString()).isEqualTo("h2")
    assertThat(Protocol.H2_PRIOR_KNOWLEDGE.toString())
      .isEqualTo("h2_prior_knowledge")
    assertThat(Protocol.QUIC.toString()).isEqualTo("quic")
    assertThat(Protocol.HTTP_3.toString()).isEqualTo("h3")
  }

import java.net.ProtocolException
import okhttp3.Protocol
import okhttp3.Response
import okio.IOException

/** An HTTP response status line like "HTTP/1.1 200 OK". */
class StatusLine(
  @JvmField val protocol: Protocol,
  @JvmField val code: Int,
  @JvmField val message: String,
) {
  override fun toString(): String =
    buildString {
      if (protocol == Protocol.HTTP_1_0) {
        append("HTTP/1.0")
      } else {