first. Fast fallback gives IPv6 connections a 250 ms head start so IPv6 is preferred on networks
where it's available.

To opt-in, configure your `OkHttpClient.Builder`:


```
OkHttpClient client = new OkHttpClient.Builder()
    .fastFallback(true)
    .build();
```

 *  New: Change the build from Kotlin-JVM to Kotlin-multiplatform (which includes JVM). Both

import java.util.concurrent.TimeUnit;
import okhttp3.Call;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;

public class CancelCall {
  private final ScheduledExecutorService executor = Executors.newScheduledThreadPool(1);
  private final OkHttpClient client = new OkHttpClient();

  public void run() throws Exception {
    Request request = new Request.Builder()

  static class Contributor {
    String login;
    int contributions;
  }

  public static void main(String... args) throws Exception {
    OkHttpClient client = new OkHttpClient();

    // Create request for remote resource.
    Request request = new Request.Builder()
        .url(ENDPOINT)
        .build();

    // Execute the request and retrieve the response.

import javax.net.ssl.SSLSession
import javax.net.ssl.SSLSocket
import okhttp3.Call
import okhttp3.Connection
import okhttp3.ConnectionSpec
import okhttp3.EventListener
import okhttp3.Handshake
import okhttp3.OkHttpClient
import okhttp3.Request
import okhttp3.TlsVersion
import okhttp3.TlsVersion.TLS_1_2
import okhttp3.TlsVersion.TLS_1_3
import okhttp3.internal.SuppressSignatureCheck

import okhttp3.Cache;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;

public final class CacheResponse {
  private final OkHttpClient client;

  public CacheResponse(File cacheDirectory) throws Exception {
    int cacheSize = 10 * 1024 * 1024; // 10 MiB
    Cache cache = new Cache(cacheDirectory, cacheSize);

    client = new OkHttpClient.Builder()
        .cache(cache)
        .build();

the `Accept-Encoding` header is not otherwise set. Web servers must be configured to return zstd
responses.

Note that zstd is not used for sending requests.

```java
OkHttpClient client = new OkHttpClient.Builder()
  .addInterceptor(ZstdInterceptor.INSTANCE)
  .build();
```

```kotlin
implementation("com.squareup.okhttp3:okhttp-zstd:0.0.0")
```

import kotlin.time.Duration
import okhttp3.Dispatcher
import okhttp3.EventListener
import okhttp3.Headers
import okhttp3.HttpUrl
import okhttp3.HttpUrl.Companion.defaultPort
import okhttp3.OkHttpClient
import okhttp3.Response
import okhttp3.internal.http2.Header
import okio.Buffer
import okio.BufferedSource
import okio.Source

/** GMT and UTC are equivalent for our purposes. */
@JvmField

import java.io.IOException
import java.net.ProtocolException
import java.util.concurrent.TimeUnit.MILLISECONDS
import okhttp3.Headers
import okhttp3.Headers.Companion.headersOf
import okhttp3.HttpUrl
import okhttp3.OkHttpClient
import okhttp3.Request
import okhttp3.Response
import okhttp3.internal.checkOffsetAndCount
import okhttp3.internal.connection.BufferedSocket
import okhttp3.internal.discard
import okhttp3.internal.headersContentLength

          if (contentLength != -1) {
            System.out.format("%d%% done\n", (100 * bytesRead) / contentLength);
          }
        }
      }
    };

    OkHttpClient client = new OkHttpClient.Builder()
        .addNetworkInterceptor(chain -> {
          Response originalResponse = chain.proceed(chain.request());
          return originalResponse.newBuilder()

import mockwebserver3.junit5.StartStop
import org.junit.jupiter.api.Test

class DispatcherCleanupTest {
  @StartStop
  private val server = MockWebServer()

  @Test
  fun testFinish() {
    val okhttp = OkHttpClient()
    val callback =
      object : Callback {
        override fun onFailure(
          call: Call,
          e: IOException,
        ) {}

        override fun onResponse(
          call: Call,