dns[PROXY_A_HOST] = dns.allocate(2)
    val selection = routeSelector.next()
    assertRoute(selection.next(), address, proxyA, dns.lookup(PROXY_A_HOST, 0), PROXY_A_PORT)
    assertRoute(selection.next(), address, proxyA, dns.lookup(PROXY_A_HOST, 1), PROXY_A_PORT)
    assertThat(selection.hasNext()).isFalse()
    assertThat(routeSelector.hasNext()).isFalse()
    dns.assertRequests(PROXY_A_HOST)

 *
 * <p>Cache statistics are incremented according to the following rules:
 *
 * <ul>
 *   <li>When a cache lookup encounters an existing cache entry {@code hitCount} is incremented.
 *   <li>When a cache lookup first encounters a missing cache entry, a new entry is loaded.
 *       <ul>
 *         <li>After successfully loading an entry {@code missCount} and {@code loadSuccessCount}

   */
  @Throws(UnknownHostException::class)
  fun lookup(hostname: String): List<InetAddress>

  companion object {
    /**
     * A DNS that uses [InetAddress.getAllByName] to ask the underlying operating system to
     * lookup IP addresses. Most custom [Dns] implementations should delegate to this instance.
     */
    @JvmField
    val SYSTEM: Dns = DnsSystem()

    static final VarHandle valueUpdater;

    static {
      MethodHandles.Lookup lookup = MethodHandles.lookup();
      try {
        waiterThreadUpdater = lookup.findVarHandle(Waiter.class, "thread", Thread.class);
        waiterNextUpdater = lookup.findVarHandle(Waiter.class, "next", Waiter.class);
        waitersUpdater =
            lookup.findVarHandle(AbstractFutureState.class, "waitersField", Waiter.class);

    assertThat(cacheEvents()).containsExactly("CacheMiss")

    result = cachedDns.lookup("google.com")
    assertThat(server.takeRequest(1, TimeUnit.MILLISECONDS)).isNull()
    assertThat(result).isEqualTo(listOf(address("157.240.1.18")))

    assertThat(cacheEvents()).containsExactly("CacheHit")

    result = cachedDns.lookup("www.google.com")
    assertThat(result).containsExactly(address("157.240.1.18"))

        headers = headersOf("Location", "http://www.fakeurl:" + server!!.port),
      ),
    )
    server!!.enqueue(MockResponse())
    val dns = FakeDns()
    dns["fakeurl"] = client.dns.lookup(server!!.hostName)
    dns["www.fakeurl"] = client.dns.lookup(server!!.hostName)
    client =
      client
        .newBuilder()
        .dns(dns)
        .build()
    val call =
      client.newCall(
        Request

 * fallbacks to guarantee that a fallback address is available.
 */
class DoubleInetAddressDns : Dns {
  override fun lookup(hostname: String): List<InetAddress> {
    val addresses = Dns.SYSTEM.lookup(hostname)
    return listOf(addresses[0], addresses[0])
  }

  const val FLAG_COMPRESSED = 0x20 // Used for data.

  /** Lookup table for valid frame types. */
  private val FRAME_NAMES =
    arrayOf(
      "DATA",
      "HEADERS",
      "PRIORITY",
      "RST_STREAM",
      "SETTINGS",
      "PUSH_PROMISE",
      "PING",
      "GOAWAY",
      "WINDOW_UPDATE",
      "CONTINUATION",
    )

  /**

 *
 *  * A DNS lookup failed
 *  * The configuration is incapable of carrying the request, such as when the client is configured
 *    to use `H2_PRIOR_KNOWLEDGE` but the URL's scheme is `https:`.
 *  * Preemptive proxy authentication failed.
 *
 * Planning failures are not necessarily fatal. For example, even if we can't DNS lookup the first
 * proxy in a list, looking up a subsequent one may succeed.

    this.replacementArray = replacementArray;
  }

  // Returns the non-null array of replacements for fast lookup.
  char[][] getReplacementArray() {
    return replacementArray;
  }

  // Creates a replacement array from the given map. The returned array is a
  // linear lookup table of replacement character sequences indexed by the
  // original character value.
  @VisibleForTesting