* HTTPS.
   */
  fun handshake(): Handshake?

  /**
   * Returns the protocol negotiated by this connection, or [Protocol.HTTP_1_1] if no protocol
   * has been negotiated. This method returns [Protocol.HTTP_1_1] even if the remote peer is using
   * [Protocol.HTTP_1_0].
   */
  fun protocol(): Protocol

   *
   * This version of OkHttp implements [RFC 7230][rfc_7230], and tracks revisions to that spec.
   *
   * [rfc_7230]: https://tools.ietf.org/html/rfc7230
   */
  HTTP_1_1("http/1.1"),

  /**
   * Chromium's binary-framed protocol that includes header compression, multiplexing multiple
   * requests on the same socket, and server-push. HTTP/1.1 semantics are layered on SPDY/3.
   *

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()
          .url("https://www.google.ca/")
          .build(),
      )
    val response = call.execute()
    try {

import okhttp3.DelegatingServerSocketFactory
import okhttp3.DelegatingSocketFactory
import okhttp3.MediaType
import okhttp3.OkHttpClient
import okhttp3.OkHttpClientTestRule
import okhttp3.Protocol.HTTP_1_1
import okhttp3.RecordingEventListener
import okhttp3.Request
import okhttp3.RequestBody
import okhttp3.SimpleProvider
import okhttp3.internal.http.CancelTest.CancelMode.CANCEL

  FRAME_SIZE_ERROR(6),

  REFUSED_STREAM(7),

  CANCEL(8),

  COMPRESSION_ERROR(9),

  CONNECT_ERROR(0xa),

  ENHANCE_YOUR_CALM(0xb),

  INADEQUATE_SECURITY(0xc),

  HTTP_1_1_REQUIRED(0xd),
  ;

  companion object {
    fun fromHttp2(code: Int): ErrorCode? = values().find { it.httpCode == code }
  }

    val request = HttpGet("https://google.com/robots.txt")

    httpClient.execute(request).use { response ->
      assertEquals(200, response.code)
      // TODO enable ALPN later
      assertEquals(HttpVersion.HTTP_1_1, response.version)
    }
  }

      "ConnectionReleased",
    )
  }

  @Test
  @Throws(IOException::class)
  fun secondCallEventSequence() {
    enableTls()
    server!!.protocols = listOf(Protocol.HTTP_2, Protocol.HTTP_1_1)
    server!!.enqueue(MockResponse())
    server!!.enqueue(MockResponse())

    client.newCall(Request(server!!.url("/")))
      .execute().close()

    client.newCall(Request(server!!.url("/")))

      response!!.closeQuietly()
    }
  }

  private fun enableHttps() {
    enableHttpsAndAlpn(Protocol.HTTP_1_1)
  }

  private fun enableHttp2() {
    platform.assumeHttp2Support()
    enableHttpsAndAlpn(Protocol.HTTP_2, Protocol.HTTP_1_1)
  }

  private fun enableHttpsAndAlpn(vararg protocols: Protocol) {
    client =
      client.newBuilder()
        .sslSocketFactory(

 *   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()
 *     }
 *
 *     return chain.proceed(chain.request())

import org.junit.jupiter.api.Test

class ProtocolTest {
  @Test
  fun testGetKnown() {
    assertThat(get("http/1.0")).isEqualTo(Protocol.HTTP_1_0)
    assertThat(get("http/1.1")).isEqualTo(Protocol.HTTP_1_1)
    assertThat(get("spdy/3.1")).isEqualTo(Protocol.SPDY_3)
    assertThat(get("h2")).isEqualTo(Protocol.HTTP_2)
    assertThat(get("h2_prior_knowledge")).isEqualTo(Protocol.H2_PRIOR_KNOWLEDGE)