*  Fix: Call `ProxySelector.connectFailed()` when a connection's initial TCP handshake fails.

 *  Fix: Change the signature of `Dispatcher` to accept a nullable `ExecutorService`. Changing this
    parameter to be non-null was an unintended signature change in OkHttp 4.0.

 *  New: `EventListener.retryDecision()` is called each time a request fails with an `IOException`.

}

public final class okhttp3/Dispatcher {
	public final fun -deprecated_executorService ()Ljava/util/concurrent/ExecutorService;
	public fun <init> ()V
	public fun <init> (Ljava/util/concurrent/ExecutorService;)V
	public final fun cancelAll ()V
	public final fun executorService ()Ljava/util/concurrent/ExecutorService;
	public final fun getIdleCallback ()Ljava/lang/Runnable;
	public final fun getMaxRequests ()I

```java
package jcifs.internal.smb2.multichannel;

import java.util.concurrent.*;

public class ChannelFailover {
    private final ChannelManager manager;
    private final ExecutorService executor;
    private final Map<String, FailoverState> failoverStates;
    
    public ChannelFailover(ChannelManager manager) {
        this.manager = manager;

      InetAddress.getByName("www.google.com")
    } catch (uhe: UnknownHostException) {
      throw TestAbortedException(uhe.message, uhe)
    }
  }

  fun OkHttpClient.close() {
    dispatcher.executorService.shutdown()
    connectionPool.evictAll()
  }

import java.util.concurrent.CancellationException;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executor;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
import java.util.concurrent.RejectedExecutionException;
import java.util.concurrent.atomic.AtomicReference;
import junit.framework.TestCase;

      <artifactId>okio</artifactId>
      <version>1.3.0</version>
    </dependency>
    ```

 *  **Fix: improve parallelism of async requests.** OkHttp's Dispatcher had a
    misconfigured `ExecutorService` that limited the number of worker threads.
    If you're using `Call.enqueue()` this update should significantly improve
    request concurrency.

   * I/O takes place.
   */
  @Test
  fun canceledBeforeIOSignalsOnFailure() {
    // Force requests to be executed serially.
    val dispatcher = Dispatcher(client.dispatcher.executorService)
    dispatcher.maxRequests = 1
    client =
      client
        .newBuilder()
        .dispatcher(dispatcher)
        .build()
    val requestA = Request(server.url("/a"))