* receiving. With duplex the request and response may be interleaved! That is, request body bytes
   * may be sent after response headers or body bytes have been received.
   *
   * Though any call may be initiated as a duplex call, only web servers that are specially
   * designed for this nonstandard interaction will use it. As of 2019-01, the only widely-used
   * implementation of this pattern is [gRPC][grpc].
   *

     * fit comfortably within a single ethernet packet (1500 bytes) even with framing overhead.
     *
     * For tests this must be big enough to realize real compression on test messages like
     * 'aaaaaaaaaa...'. Our tests check if compression was applied just by looking at the size if
     * the inbound buffer.
     */

      // Flow control was designed more for servers, or proxies than edge clients. If we are a client,
      // set the flow control window to 16MiB.  This avoids thrashing window updates every 64KiB, yet
      // small enough to avoid blowing up the heap.
      if (builder.client) {
        set(Settings.INITIAL_WINDOW_SIZE, OKHTTP_CLIENT_WINDOW_SIZE)
      }
    }

  /**

    initialize the response cache.
 *  New: Fold `MockWebServerRule` into `MockWebServer`. This makes it easier to
    write JUnit tests with `MockWebServer`. The `MockWebServer` library now
    depends on JUnit, though it continues to work with all testing frameworks.
 *  Fix: `FormEncodingBuilder` is now consistent with browsers in which
    characters it escapes. Previously we weren’t percent-encoding commas,
    parens, and other characters.

   * structures.
   *
   * We make such subtle calls in [okhttp3.internal.ws.MessageInflater] because we try to read a
   * compressed stream that is terminated in a web socket frame even though the DEFLATE stream is
   * not terminated.
   *
   * Use this method to create a degenerate Okio Buffer where each byte is in a separate segment of
   * the internal list.
   */
  @JvmStatic

    addressStates[address]?.scheduleOpener()
  }

  fun scheduleCloser() {
    cleanupQueue.schedule(cleanupTask)
  }

  /**
   * Ensure enough connections open to [address] to satisfy its [ConnectionPool.AddressPolicy].
   * If there are already enough connections, we're done.
   * If not, we create one and then schedule the task to run again immediately.
   */
  private fun openConnections(state: AddressState): Long {

      assertEquals(200, response.code)
    }

    client.connectionPool.evictAll()
    assertEquals(0, client.connectionPool.connectionCount())

    // Force reuse. This appears flaky (30% of the time) even though sessions are reused.
    // javax.net.ssl.SSLHandshakeException: No new session is allowed and no existing
    // session can be resumed
    //
    // Report https://bugs.java.com/bugdatabase/view_bug.do?bug_id=JDK-8264944

      Request.Builder()
        .url(server.url("/"))
        .post(AsyncRequestBody())
        .build()
    val call = client.newCall(request)
    call.timeout()
      .timeout(500, TimeUnit.MILLISECONDS) // Long enough for the first TLS handshake.
    call.execute().use { response ->
      val requestBody = (call.request().body as AsyncRequestBody?)!!.takeSink()
      val responseBody = response.body.source()

  /** Returns the trailers after the HTTP response. May be empty. */
  @Throws(IOException::class)
  fun trailers(): Headers

  /**
   * Cancel this stream. Resources held by this stream will be cleaned up, though not synchronously.
   * That may happen later by the connection pool thread.
   */
  fun cancel()

  /**
   * Carries an exchange. This is usually a connection, but it could also be a connect plan for

OkHttpClient client = new OkHttpClient.Builder()
    .sslSocketFactory(clientCertificates.sslSocketFactory(), clientCertificates.trustManager())
    .build();
```

With a server that holds a certificate and a client that trusts it we have enough for an HTTPS
handshake. The best part of this example is that we don't need to make our test code insecure with a
a fake `HostnameVerifier` or `X509TrustManager`.

Certificate Authorities
-----------------------