*    we must send a `CONNECT` request, and handle authorization challenges from the proxy.
 *  * Optional [TLS handshake][connectTls].
 *
 * Each step may fail. If a retry is possible, a new instance is created with the next plan, which
 * will be configured differently.
 */
class ConnectPlan(
  private val taskRunner: TaskRunner,
  private val connectionPool: RealConnectionPool,

            "Close",
            "Retry-After",
            "0",
          ),
        body = "You took too long!",
        socketPolicy = DisconnectAtEnd,
      ),
    )
    server.enqueue(
      MockResponse(
        code = 503,
        headers =
          headersOf(
            "Connection",
            "Close",
            "Retry-After",
            "0",
          ),

  /**
   * Returns the response for the HTTP redirect or authorization challenge that triggered this
   * response, or null if this response wasn't triggered by an automatic retry. The body of the
   * returned response should not be read because it has already been consumed by the redirecting
   * client.
   */
  @get:JvmName("priorResponse") val priorResponse: Response?,
  /**

    // Set up a same-connection retry.
    serverIpv4.enqueue(
      MockResponse(socketPolicy = ResetStreamAtStart(ErrorCode.REFUSED_STREAM.httpCode)),
    )
    serverIpv4.enqueue(
      MockResponse(body = "this was the 2nd request on IPv4"),
    )
    serverIpv6.enqueue(
      MockResponse(body = "unexpected call to IPv6"),
    )

    // Confirm the retry succeeds on the same connection.

## Retrying Requests

Sometimes connections fail: either a pooled connection was stale and disconnected, or the webserver itself couldn’t be reached. OkHttp will retry the request with a different route if one is available.

## [Calls](https://square.github.io/okhttp/4.x/okhttp/okhttp3/-call/)

 *  Fix: Don't miss whole operation timeouts when calls redirect.
 *  Fix: Don't leak connections if web sockets have malformed responses or if `onOpen()` throws.
 *  Fix: Don't retry when request bodies fail due to `FileNotFoundException`.
 *  Fix: Don't crash when URLs have IPv4-mapped IPv6 addresses.
 *  Fix: Don't crash when building `HandshakeCertificates` on Android API 28.

There may be many routes for a single address. For example, a webserver that is hosted in multiple datacenters may yield multiple IP addresses in its DNS response.

In limited situations OkHttp will retry a route if connecting fails:

    assertThat(response.body.string()).isEqualTo("abc")
    assertThat(server.takeRequest().sequenceNumber).isEqualTo(0)

    // Note that although we have two routes available, we only use one. The retry is permitted
    // because there are routes available, but it chooses the existing connection since it isn't
    // yet considered unhealthy.
    assertThat(server.takeRequest().sequenceNumber).isEqualTo(1)
  }

    val uri = newBuilder().reencodeForUri().toString()
    return try {
      URI(uri)
    } catch (e: URISyntaxException) {
      // Unlikely edge case: the URI has a forbidden character in the fragment. Strip it & retry.
      try {
        val stripped = uri.replace(Regex("[\\u0000-\\u001F\\u007F-\\u009F\\p{javaWhitespace}]"), "")
        URI.create(stripped)
      } catch (e1: Exception) {

      // If the problem was a CertificateException from the X509TrustManager,
      // do not retry.
      if (e.cause is CertificateException) {
        return false
      }
    }
    if (e is SSLPeerUnverifiedException) {
      // e.g. a certificate pinning error.
      return false
    }
    // An example of one we might want to retry with a different route is a problem connecting to a