}

  override fun getSelectedProtocol(sslSocket: SSLSocket): String? =
    if (sslSocket is org.openjsse.javax.net.ssl.SSLSocket) {
      when (val protocol = sslSocket.applicationProtocol) {
        // Handles both un-configured and none selected.
        null, "" -> null
        else -> protocol
      }
    } else {
      super.getSelectedProtocol(sslSocket)
    }

  companion object {
    val isSupported: Boolean =
      try {

If the response issues an authorization challenge, OkHttp will ask the [`Authenticator`](https://square.github.io/okhttp/4.x/okhttp/okhttp3/-authenticator/) (if one is configured) to satisfy the challenge. If the authenticator supplies a credential, the request is retried with that credential included.

## Retrying Requests

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

When you request a URL with OkHttp, here's what it does:

 1. It uses the URL and configured OkHttpClient to create an **address**. This address specifies how we'll connect to the webserver.
 2. It attempts to retrieve a connection with that address from the **connection pool**.

    interceptor.


## Version 3.10.0

_2018-02-24_

 *  **The pingInterval() feature now aggressively checks connectivity for web
    sockets and HTTP/2 connections.**

    Previously if you configured a ping interval that would cause OkHttp to send
    pings, but it did not track whether the reply pongs were received. With this
    update OkHttp requires that every ping receive a response: if it does not

/**
 * Apply this rule to all tests. It adds additional checks for leaked resources and uncaught
 * exceptions.
 *
 * Use [newClient] as a factory for a OkHttpClient instances. These instances are specifically
 * configured for testing.
 */
class OkHttpClientTestRule : BeforeEachCallback, AfterEachCallback {
  private val clientEventsList = mutableListOf<String>()
  private var testClient: OkHttpClient? = null

/**
 * The concrete route used by a connection to reach an abstract origin server. When creating a
 * connection the client has many options:
 *
 *  * **HTTP proxy:** a proxy server may be explicitly configured for the client. Otherwise, the
 *    [proxy selector][java.net.ProxySelector] is used. It may return multiple proxies to attempt.
 *  * **IP address:** whether connecting directly to an origin server or a proxy, opening a socket

first connect fails. This is necessary for IPv4+IPv6 and services hosted in redundant data
centers. OkHttp supports modern TLS features (TLS 1.3, ALPN, certificate pinning). It can be
configured to fall back for broad connectivity.

Using OkHttp is easy. Its request/response API is designed with fluent builders and immutability. It
supports both synchronous blocking calls and async calls with callbacks.

/**
 * Policy on when async requests are executed.
 *
 * Each dispatcher uses an [ExecutorService] to run calls internally. If you supply your own
 * executor, it should be able to run [the configured maximum][maxRequests] number of calls
 * concurrently.
 */
class Dispatcher() {
  internal val lock: ReentrantLock = ReentrantLock()

  /**

    val location = userResponse.header("Location") ?: return null
    // Don't follow redirects to unsupported protocols.
    val url = userResponse.request.url.resolve(location) ?: return null

    // If configured, don't follow redirects between SSL and non-SSL.
    val sameScheme = url.scheme == userResponse.request.url.scheme
    if (!sameScheme && !client.followSslRedirects) return null

 *  New: Add `Call.isExecuted()`.


## Version 2.6.0

_2015-11-22_

 *  **New Logging Interceptor.** The `logging-interceptor` subproject offers
    simple request and response logging. It may be configured to log headers and
    bodies for debugging. It requires this Maven dependency:

     ```xml
     <dependency>
       <groupId>com.squareup.okhttp</groupId>
       <artifactId>logging-interceptor</artifactId>