/** Returns the trailers after the HTTP response. May be empty. */
  @Throws(IOException::class)
  fun trailers(): Headers

  /**
   * Cancel this stream. Resources held by this stream will be cleaned up, though not synchronously.
   * That may happen later by the connection pool thread.
   */
  fun cancel()

  /**
   * Carries an exchange. This is usually a connection, but it could also be a connect plan for

    stream = http2Connection.newStream(requestHeaders, hasRequestBody)
    // We may have been asked to cancel while creating the new stream and sending the request
    // headers, but there was still no stream to close.
    if (canceled) {
      stream!!.closeLater(ErrorCode.CANCEL)
      throw IOException("Canceled")
    }
    stream!!.readTimeout().timeout(chain.readTimeoutMillis.toLong(), TimeUnit.MILLISECONDS)

  override fun connectTcp() = error("already connected")

  override fun connectTlsEtc() = error("already connected")

  override fun handleSuccess() = connection

  override fun cancel() = error("unexpected cancel")

  override fun retry() = error("unexpected retry")

   * stream was canceled.
   *
   * This does nothing if [requestBody] and [responseBody] are already closed.
   *
   * For HTTP/2 this sends the [CANCEL](https://datatracker.ietf.org/doc/html/rfc7540#section-7)
   * error code.
   */
  fun cancel()

        .build()

    val startNanos = System.nanoTime()
    val call = client.newCall(request)

    // Schedule a job to cancel the call in 1 second.
    executor.schedule({
      System.out.printf("%.2f Canceling call.%n", (System.nanoTime() - startNanos) / 1e9f)
      call.cancel()
      System.out.printf("%.2f Canceled call.%n", (System.nanoTime() - startNanos) / 1e9f)
    }, 1, TimeUnit.SECONDS)

  fun noNewExchangesOnConnection() {
    codec.carrier.noNewExchanges()
  }

  fun cancel() {
    codec.cancel()
  }

  /**
   * Revoke this exchange's access to streams. This is necessary when a follow-up request is
   * required but the preceding exchange hasn't completed yet.
   */
  fun detachWithViolence() {
    codec.cancel()
    call.messageDone(this, requestDone = true, responseDone = true, e = null)
  }

   */
  fun cancel()

  fun interface Factory {
    /**
     * Creates a new web socket and immediately returns it. Creating a web socket initiates an
     * asynchronous process to connect the socket. Once that succeeds or fails, `listener` will be
     * notified. The caller must either close or cancel the returned web socket when it is no longer
     * in use.
     */

 * response data before all request data has been received.
 *
 * See [okhttp3.RequestBody.isDuplex].
 */
@ExperimentalOkHttpApi
interface StreamHandler {
  fun handle(stream: Stream)