)
    serverIpv4.protocols = listOf(Protocol.H2_PRIOR_KNOWLEDGE)
    serverIpv6.protocols = listOf(Protocol.H2_PRIOR_KNOWLEDGE)

    // Yield the first IP address so the second IP address completes first.
    val firstConnectLatch = CountDownLatch(1)
    val socketFactory =
      object : DelegatingSocketFactory(SocketFactory.getDefault()) {
        var first = true

    taskRunner.lock.withLock {
      check(currentTask == TestThreadSerialTask)
      nanoTime = newTime
      yieldUntil(ResumePriority.AfterOtherTasks)
    }
  }

  /** Confirm all tasks have completed. Used by the test thread only. */
  fun assertNoMoreTasks() {
    taskRunner.assertThreadDoesntHoldLock()

    taskRunner.lock.withLock {
      assertThat(activeThreads).isEqualTo(0)
    }
  }

      HandshakeCertificates.Builder()
        .heldCertificate(certificate, intermediateCa.certificate)
        .build()
    server.useHttps(serverHandshakeCertificates.sslSocketFactory())

    // The request should complete successfully.
    server.enqueue(
      MockResponse.Builder()
        .body("abc")
        .build(),
    )
    val call1 =
      client.newCall(
        Request.Builder()

  return (
    readByte() and 0xff shl 16
      or (readByte() and 0xff shl 8)
      or (readByte() and 0xff)
  )
}

/** Run [block] until it either throws an [IOException] or completes. */
internal inline fun ignoreIoExceptions(block: () -> Unit) {
  try {
    block()
  } catch (_: IOException) {
  }
}

internal fun Buffer.skipAll(b: Byte): Int {
  var count = 0

 * Attempting to create new streams on these allocations will fail.
 *
 * Note that an allocation may be released before its stream is completed. This is intended to make
 * bookkeeping easier for the caller: releasing the allocation as soon as the terminal stream has
 * been found. But only complete the stream once its data stream has been exhausted.
 */
interface Connection {
  /** Returns the route used by this connection. */

    // the connection flow-control window so new requests can proceed.
    call1.cancel()
    assertThat(
      response1.body.source().discard(1, TimeUnit.SECONDS),
      "Call should not have completed successfully.",
    ).isFalse()
    val call2 = client.newCall(Request(server.url("/")))
    val response2 = call2.execute()
    assertThat(response2.body.string()).isEqualTo("abc")
  }

    }, 1, TimeUnit.SECONDS);

    System.out.printf("%.2f Executing call.%n", (System.nanoTime() - startNanos) / 1e9f);
    try (Response response = call.execute()) {
      System.out.printf("%.2f Call was expected to fail, but completed: %s%n",
          (System.nanoTime() - startNanos) / 1e9f, response);
    } catch (IOException e) {
      System.out.printf("%.2f Call failed as expected: %s%n",
          (System.nanoTime() - startNanos) / 1e9f, e);
    }

   *
   * This method returns false unless it is overridden by a subclass.
   *
   * ### Duplex Transmission
   *
   * With regular HTTP calls the request always completes sending before the response may begin
   * receiving. With duplex the request and response may be interleaved! That is, request body bytes
   * may be sent after response headers or body bytes have been received.
   *

        ) {
          promise.completeExceptionally(e)
        }

        override fun onResponse(
          call: Call,
          response: Response,
        ) {
          promise.complete(response)
        }
      },
    )

    val response = promise.get(4, SECONDS)

    assertThat(response).isNotNull()

    assertThat(response.body.string()).isNotEmpty()

 * HTTP/2 support allows all requests to the same host to share a socket.
 * Connection pooling reduces request latency (if HTTP/2 isn’t available).
 * Transparent GZIP shrinks download sizes.
 * Response caching avoids the network completely for repeat requests.

OkHttp perseveres when the network is troublesome: it will silently recover from common connection
problems. If your service has multiple IP addresses, OkHttp will attempt alternate addresses if the