* </ul>
 *
 * <h4>{@link java.util.concurrent.CompletableFuture} / {@link java.util.concurrent.CompletionStage}
 * </h4>
 *
 * <p>Users of {@code CompletableFuture} will likely want to continue using {@code
 * CompletableFuture}. {@code FluentFuture} is targeted at people who use {@code ListenableFuture},
 * who can't use Java 8, or who want an API more focused than {@code CompletableFuture}. (If you

    val negotiatedProtocol: String,
    val content: String,
  )

  private fun execute(
    engine: HttpEngine,
    executor: ExecutorService,
    url: String,
  ): CompletableFuture<Response> {
    val completableFuture = CompletableFuture<Response>()
    val buffer = Buffer()

    val req =
      engine
        .newUrlRequestBuilder(
          url,
          executor,
          object : Callback {

import assertk.assertions.startsWith
import assertk.fail
import java.io.IOException
import java.net.ServerSocket
import java.net.Socket
import java.net.SocketException
import java.util.concurrent.CompletableFuture
import java.util.concurrent.RejectedExecutionException
import java.util.concurrent.TimeUnit
import kotlin.test.assertFailsWith
import okhttp3.Call
import okhttp3.Callback
import okhttp3.DelegatingServerSocketFactory

import assertk.assertThat
import assertk.assertions.isEqualTo
import assertk.assertions.isNotEmpty
import assertk.assertions.isNotNull
import java.io.IOException
import java.net.InetAddress
import java.util.concurrent.CompletableFuture
import java.util.concurrent.TimeUnit.SECONDS
import javax.net.ssl.SNIHostName
import javax.net.ssl.SNIMatcher
import javax.net.ssl.SNIServerName
import javax.net.ssl.SSLSocket
import javax.net.ssl.StandardConstants

 * that, whenever possible, it is strongly preferred to modify those libraries to return {@code
 * ListenableFuture} directly.
 *
 * <p>For interoperability between {@code ListenableFuture} and <b>{@code CompletableFuture}</b>,
 * consider <a href="https://github.com/lukas-krecan/future-converter">Future Converter</a>.
 *
 * @author Sven Mawson
 * @since 10.0 (replacing {@code Futures.makeListenable}, which existed in 1.0)
 */

 *
 * <p>Caffeine's API for asynchronous operations uses {@code CompletableFuture}: <a
 * href="https://www.javadoc.io/doc/com.github.ben-manes.caffeine/caffeine/latest/com.github.benmanes.caffeine/com/github/benmanes/caffeine/cache/AsyncLoadingCache.html#get(K)">{@code
 * AsyncLoadingCache.get}</a> returns a {@code CompletableFuture}, and implementations of <a

 *
 * <p>Caffeine's API for asynchronous operations uses {@code CompletableFuture}: <a
 * href="https://www.javadoc.io/doc/com.github.ben-manes.caffeine/caffeine/latest/com.github.benmanes.caffeine/com/github/benmanes/caffeine/cache/AsyncLoadingCache.html#get(K)">{@code
 * AsyncLoadingCache.get}</a> returns a {@code CompletableFuture}, and implementations of <a