* </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.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)
 */

 * 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