### Events with Retries and Follow-Ups

OkHttp is resilient and can automatically recover from some connectivity failures. In this case, the `connectFailed()` event is not terminal and not followed by `callFailed()`. Event listeners will receive multiple events of the same type when retries are attempted.

    Get these strings with `HeldCertificate.certificatePem()` and `privateKeyPkcs8Pem()`.

 *  Fix: Handshake now returns peer certificates in canonical order: each certificate is signed by
    the certificate that follows and the last certificate is signed by a trusted root.

 *  Fix: Don't lose HTTP/2 flow control bytes when incoming data races with a stream close. If this
    happened enough then eventually the connection would stall.

    }
    serverWriter.writeMessageFrame(OPCODE_BINARY, payload.snapshot())

    // Write directly to the unbuffered sink. This ensures it will become single frame.
    assertData("827e") // 'e' == 4-byte follow-up length.
    assertData(format("%04X", payload.completeSegmentByteCount()))
    assertData(payload.readByteString())
  }

  @Test fun serverMessageLengthLong() {

   * OkHttp in the current runtime. Use this to include the OkHttp version in custom `User-Agent`
   * headers.
   *
   * Official OkHttp releases follow [semantic versioning][semver]. Versions with the `-SNAPSHOT`
   * qualifier are not unique and should only be used in development environments. If you create

    assertThat(request.headers["Accept-Encoding"]).isEqualTo("custom")
  }

  /**
   * Test a bug where gzip input streams weren't exhausting the input stream, which corrupted the
   * request that followed or prevented connection reuse. http://code.google.com/p/android/issues/detail?id=7059
   * http://code.google.com/p/android/issues/detail?id=38817
   */
  private fun testClientConfiguredGzipContentEncodingAndConnectionReuse(

  val callTimeout: Int by option(
    "--call-timeout",
    help = "Maximum time allowed for the entire call (seconds)",
  ).int().default(DEFAULT_TIMEOUT)

  val followRedirects: Boolean by option("-L", "--location", help = "Follow redirects").flag()

  val allowInsecure: Boolean by option("-k", "--insecure", help = "Allow connections to SSL sites without certs").flag()

 *         .build();
 *   }
 * }
 * return null; // Didn't find a preemptive auth scheme.
 * ```
 *
 * ## Reactive Authentication
 *
 * Implementations authenticate by returning a follow-up request that includes an authorization
 * header, or they may decline the challenge by returning null. In this case the unauthenticated
 * response will be returned to the caller that triggered it.
 *

      )

    call.execute().use { response ->
      assertThat(response.body.string()).isEqualTo("abc")
      assertThat(response.trailers()).isEqualTo(headersOf("caboose", "xyz"))
    }
  }

  @Disabled("Follow up with fix in https://github.com/square/okhttp/issues/6853")
  @Test
  fun serverDisconnectsBeforeSecondRequestHttp1() {
    enableProtocol(Protocol.HTTP_1_1)

    server.enqueue(MockResponse(code = 200, body = "Req1"))

 * save a small amount of file I/O and data copying.
 */
class Relay private constructor(
  /**
   * Read/write persistence of the upstream source and its metadata. Its layout is as follows:
   *
   *  * 16 bytes: either `OkHttp cache v1\n` if the persisted file is complete. This is another
   *    sequence of bytes if the file is incomplete and should not be used.
   *  * 8 bytes: *n*: upstream data size

   */
  open fun cacheMiss(call: Call) {
  }

  /**
   * Invoked when a response will be served from the cache or network based on validating the
   * cached Response freshness. Will be followed by cacheHit or cacheMiss after the network
   * Response is available.
   *
   * This event will only be received when a Cache is configured for the client.
   */
  open fun cacheConditionalHit(
    call: Call,