interceptors@2x.png...

 *   }
 * ```
 */
fun interface Interceptor {
  @Throws(IOException::class)
  fun intercept(chain: Chain): Response

  companion object {
    /**
     * Constructs an interceptor for a lambda. This compact syntax is most useful for inline
     * interceptors.
     *
     * ```kotlin
     * val interceptor = Interceptor { chain: Interceptor.Chain ->
     *     chain.proceed(chain.request())
     * }

    // Call the next interceptor in the chain.
    val next = copy(index = index + 1, request = request)
    val interceptor = interceptors[index]

    @Suppress("USELESS_ELVIS")
    val response =
      interceptor.intercept(next) ?: throw NullPointerException(
        "interceptor $interceptor returned null",
      )

    if (exchange != null) {
      check(index + 1 >= interceptors.size || next.calls == 1) {

        'calls.md': 'features/calls.md'
        'connections.md': 'features/connections.md'
        'events.md': 'features/events.md'
        'https.md': 'features/events.md'
        'interceptors.md': 'features/interceptors.md'
        'r8_proguard.md': 'features/r8_proguard.md'
        # Redirect all Security pages to security/*
        'security.md': 'security/security.md'

    // Build a full stack of interceptors.
    val interceptors = mutableListOf<Interceptor>()
    interceptors += client.interceptors
    interceptors += RetryAndFollowUpInterceptor(client)
    interceptors += BridgeInterceptor(client.cookieJar)
    interceptors += CacheInterceptor(this, client.cache)
    interceptors += ConnectInterceptor
    if (!forWebSocket) {
      interceptors += client.networkInterceptors
    }

    running SSLv3, you must manually configure your own `ConnectionSpec`.

 *  **OkHttp now offers interceptors.** Interceptors are a powerful mechanism
    that can monitor, rewrite, and retry calls. The [interceptors doc][interceptors] is a full
    introduction to this new API.

 *  New: APIs to iterate and selectively clear the response cache.
 *  New: Support for SOCKS proxies.

  @Test fun clonedInterceptorsListsAreIndependent() {
    val interceptor =
      Interceptor { chain: Interceptor.Chain ->
        chain.proceed(chain.request())
      }
    val original = clientTestRule.newClient()
    original
      .newBuilder()
      .addInterceptor(interceptor)
      .addNetworkInterceptor(interceptor)
      .build()
    assertThat(original.interceptors.size).isEqualTo(0)

    builder = builder.encodedFragment("")
    val httpUrl: HttpUrl = builder.build()
  }

  @Test
  fun interceptor() {
    var interceptor: Interceptor = Interceptor { TODO() }
    interceptor = Interceptor { it: Interceptor.Chain -> TODO() }
  }

  @Test
  fun interceptorChain() {
    val chain: Interceptor.Chain = newInterceptorChain()
  }

  @Test
  fun handshakeCertificates() {

    val proxy: Proxy? = client.proxy()
    val protocols: List<Protocol> = client.protocols()
    val connectionSpecs: List<ConnectionSpec> = client.connectionSpecs()
    val interceptors: List<Interceptor> = client.interceptors()
    val networkInterceptors: List<Interceptor> = client.networkInterceptors()
    val eventListenerFactory: EventListener.Factory = client.eventListenerFactory()
    val proxySelector: ProxySelector = client.proxySelector()

Cleanup_ for a safe and fast upgrade.


Backwards-Incompatible Changes
------------------------------

#### OkHttpClient final methods

`OkHttpClient` has 26 accessors like `interceptors()` and `writeTimeoutMillis()` that were non-final
in OkHttp 3.x and are final in 4.x. These were made non-final for use with mocking frameworks like