val call = client.newCall(Request(url))
    val response = call.execute()
    assertThat(response.body.string()).isEqualTo("hello from IPv6")

    // In the process we made two connection attempts including one failure.
    assertThat(listener.recordedEventTypes().filter { it == "ConnectStart" }).hasSize(1)
    assertThat(listener.recordedEventTypes().filter { it == "ConnectEnd" }).hasSize(1)

    return client.newCall(request).execute()
  }

  /**
   * @param delta the offset from the current date to use. Negative values yield dates in the past;
   *     positive values yield dates in the future.
   */
  private fun formatDate(
    delta: Long,
    timeUnit: TimeUnit,
  ): String? {
    return formatDate(Date(System.currentTimeMillis() + timeUnit.toMillis(delta)))
  }

Once the response has been received, the connection will be returned to the pool so it can be reused for a future request. Connections are evicted from the pool after a period of inactivity.

### [Fast Fallback](https://square.github.io/okhttp/4.x/okhttp/okhttp3/-ok-http-client/-builder/fast-fallback/)

## Version 1.5.1

_2014-03-11_

 * Fix 1.5.0 regression where connections should not have been recycled.
 * Fix 1.5.0 regression where transparent Gzip was broken by attempting to
   recover from another I/O failure.
 * Fix problems where spdy/3.1 headers may not have been compressed properly.
 * Fix problems with spdy/3.1 and http/2 where the wrong window size was being
   used.

        .build()
    val call = client.newCall(request)
    call.enqueue(callback)
    val recordedResponse = callback.await(server.url("/"))
    assertThat(recordedResponse.failure, "canceled due to java.lang.RuntimeException: boom!")
    recordedResponse.failure!!.assertSuppressed { throwables: List<Throwable>? ->
      assertThat(throwables!!).contains(boom)
      Unit
    }
    assertThat(call.isCanceled()).isTrue()

 *     try (ResponseBody responseBody = response.body()) {
 *     ... // Use the response.
 *     }
 *   }
 *
 *   public void onFailure(Call call, IOException e) {
 *   ... // Handle the failure.
 *   }
 * });
 * ```
 *
 * These examples will not work if you're consuming the response body on another thread. In such
 * cases the consuming thread must call [close] when it has finished reading the response

internal fun FileSystem.deleteIfExists(path: Path) {
  try {
    delete(path)
  } catch (fnfe: FileNotFoundException) {
    return
  }
}

/** Tolerant delete, try to clear as many files as possible even after a failure. */
internal fun FileSystem.deleteContents(directory: Path) {
  var exception: IOException? = null
  val files =
    try {
      list(directory)
    } catch (fnfe: FileNotFoundException) {
      return

 *  New: We've added `requestFailed()` and `responseFailed()` methods to `EventListener`. These
    are called instead of `requestBodyEnd()` and `responseBodyEnd()` in some failure situations.
    They may also be fired in cases where no event was published previously. In this release we did
    an internal rewrite of our event code to fix problems where events were lost or unbalanced.

direct, indirect, special, incidental, or consequential damages of any character arising as a result of this License or out of the use or inability to use the Work (including but not limited to damages for loss of goodwill, work stoppage, computer failure or malfunction, or any and all other commercial damages or losses), even if such Contributor has been advised of the possibility of such damages. 9. Accepting Warranty or Additional Liability. While redistributing the Work or Derivative Works thereof,...

    assertFailsWith<IOException> {
      call.execute()
    }.also { expected ->
      assertThat(call.isCanceled()).isTrue()
    }
    val recordedRequest = server.takeRequest()
    assertThat(recordedRequest.failure!!).hasMessage("stream was reset: CANCEL")
  }

  @ParameterizedTest
  @ArgumentsSource(ProtocolParamProvider::class)
  fun http2WithProxy(
    protocol: Protocol,
    mockWebServer: MockWebServer,