### 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.

    }
    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

    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()

  val showHeaders: Boolean by option("-i", "--include", help = "Include protocol headers in the output").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.
 *

 *  Fix: Don't crash with a `NullPointerException` if a server sends a close while we're sending a
    ping. OkHttp had a race condition bug.


## Version 4.6.0

_2020-04-28_

 *  Fix: Follow HTTP 307 and 308 redirects on methods other than GET and POST. We're reluctant to
    change OkHttp's behavior in handling common HTTP status codes, but this fix is overdue! The new

      )

    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"))

    )

    // No authorization header for the first request...
    var request = server.takeRequest()
    assertThat(request.headers["Authorization"]).isNull()

    // ...but the three requests that follow include an authorization header.
    for (i in 0..2) {
      request = server.takeRequest()
      assertThat(request.requestLine).isEqualTo("POST / HTTP/1.1")
      assertThat(request.headers["Authorization"]).isEqualTo(

can make. We therefore encourage reporting security issues with the code
contained in this repository.

If you believe you have discovered a security vulnerability, please follow the
guidelines at https://bugcrowd.com/squareopensource


## Verifying Artifacts

We sign our artifacts using this [key][signing_key]:

```

      requestBody.close()
      assertThat(responseBody.readUtf8Line()).isNull()
    }
    body.awaitSuccess()
  }

  /**
   * Duplex calls that have follow-ups are weird. By the time we know there's a follow-up we've
   * already split off another thread to stream the request body. Because we permit at most one
   * exchange at a time we break the request stream out from under that writer.
   */
  @Test