locality and performance OkHttp attempts to use the same pooled connection across redirects and
    follow-ups. It independently shares connections when the IP addresses and certificates match,
    even if the host names do not. In 4.4.0 we introduced a regression where we shared a connection

    var routeSelector = newRouteSelector(address)
    dns[PROXY_A_HOST] = dns.allocate(1)
    dns[PROXY_B_HOST] = dns.allocate(1)

    // Mark the ProxyA route as failed.
    val selection = routeSelector.next()
    dns.assertRequests(PROXY_A_HOST)
    val route = selection.next()
    assertRoute(route, address, proxyA, dns.lookup(PROXY_A_HOST, 0), PROXY_A_PORT)
    routeDatabase.failed(route)

Kotlin calling OkHttp 3.x:

```kotlin
val client = OkHttpClient.Builder()
    .dns { hostname -> InetAddress.getAllByName(hostname).toList() }
    .build()
```

Kotlin calling OkHttp 4.x:

```kotlin
val client = OkHttpClient.Builder()
    .dns(object : Dns {
      override fun lookup(hostname: String) =
          InetAddress.getAllByName(hostname).toList()
    })

   * {@code A -> B}.
   *
   * @since 9.0 (in 1.0 as {@code com.google.common.base.Service.State})
   */
  enum State {
    /** A service in this state is inactive. It does minimal work and consumes minimal resources. */
    NEW,

    /** A service in this state is transitioning to {@link #RUNNING}. */
    STARTING,

    /** A service in this state is operational. */
    RUNNING,

 * `::1` will reach the IPv6 server.
 *
 * By orchestrating two different servers with the same port but different IP addresses, we can
 * test what OkHttp does when both are reachable, or if only one is reachable.
 *
 * This test only runs on host machines that have both IPv4 and IPv6 addresses for localhost.
 */
@Timeout(30)
class FastFallbackTest {
  @RegisterExtension

  /**
   * When we need a new thread to run tasks, we call [Backend.execute]. A few microseconds later we
   * expect a newly-started thread to call [Runnable.run]. We shouldn't request new threads until
   * the already-requested ones are in service, otherwise we might create more threads than we need.
   *
   * We use [executeCallCount] and [runCallCount] to defend against starting more threads than we
   * need. Both fields are guarded by `this`.
   */

    this.table = table;
    this.mask = mask;
  }

  /**
   * Checks if the given key already appears in the hash chain starting at {@code keyBucketHead}. If
   * it does not, then null is returned. If it does, then if {@code throwIfDuplicateKeys} is true an
   * {@code IllegalArgumentException} is thrown, and otherwise the existing {@link Entry} is
   * returned.
   *

This release also stabilizes many APIs in the `mockwebserver3` artifact that's new in 5.0.

 *  Breaking: `RecordedRequest.body` is now nullable. Null is used when the request does not have a
    body.

 *  Breaking: `RecordedRequest.chunkSizes` is now nullable. Null is used when the request does not
    use chunked encoding. This is different from an empty list - that indicates the request is
    chunked but has no data.

         configurations downstream, and GWT uses the runtime configuration for
         its builds. Thus, GWT doesn't get j2objc-annotations transitively, in
         contrast to the other deps of `guava`, which it does get transitively.
         (Arguably we should redeclare *all* the `guava` deps here.) -->
    <dependency>
      <groupId>com.google.j2objc</groupId>
      <artifactId>j2objc-annotations</artifactId>
    </dependency>

    return asImmutableList(array);
  }

  /** Views the array as an immutable list. Checks for nulls; does not copy. */
  private static <E> ImmutableList<E> construct(Object... elements) {
    return asImmutableList(checkElementsNotNull(elements));
  }

  /**
   * Views the array as an immutable list. Does not check for nulls; does not copy.
   *
   * <p>The array must be internally created.
   */