internal fun reorderForHappyEyeballs(addresses: List<InetAddress>): List<InetAddress> {
  if (addresses.size < 2) {
    return addresses
  }

  val (ipv6, ipv4) = addresses.partition { it is Inet6Address }

  return if (ipv6.isEmpty() || ipv4.isEmpty()) {
    addresses
  } else {
    interleave(ipv6, ipv4)
  }

   *   <li>An IPv6 address string with or without brackets, like {@code [2001:db8::1]} or {@code
   *       2001:db8::1}
   * </ul>
   *
   * @throws IllegalArgumentException if the specifier is not valid.
   */
  public static HostSpecifier fromValid(String specifier) {
    // Verify that no port was specified, and strip optional brackets from
    // IPv6 literals.

     */
    @Override
    public InetAddress[] resolve(final String host) throws UnknownHostException {
        // Handle IPv6 addresses in bracket notation
        if (host != null && host.length() > 2 && host.startsWith("[") && host.endsWith("]")) {
            // Remove brackets for IPv6 address resolution
            final String ipv6Address = host.substring(1, host.length() - 1);

    Collections.synchronizedMap(mutableMapOf())
  private val requestedHosts: MutableList<String> = Collections.synchronizedList(mutableListOf())
  private var nextAddress = 0xff000064L // 255.0.0.100 in IPv4; ::ff00:64 in IPv6.

  /** Sets the results for `hostname`.  */
  operator fun set(
    hostname: String,
    addresses: List<InetAddress>,
  ): FakeDns {
    hostAddresses[hostname] = addresses
    return this
  }

     * @return IP address
     */
    public InetAddress getAddress() {
        return address;
    }

    /**
     * Check if this is an IPv6 address
     *
     * @return true if IPv6, false if IPv4
     */
    public boolean isIpv6() {
        return ipv6;
    }

    /**
     * Check if RSS is supported
     *
     * @return true if RSS capable
     */
    public boolean isRssCapable() {

     */
    @Override
    public InetAddress[] resolve(final String host) throws UnknownHostException {
        // Handle IPv6 addresses in bracket notation
        if (host != null && host.length() > 2 && host.startsWith("[") && host.endsWith("]")) {
            // Remove brackets for IPv6 address resolution
            final String ipv6Address = host.substring(1, host.length() - 1);

        .testEquals();
  }

  public void testRequireBracketsForIPv6() {
    // Bracketed IPv6 works fine.
    assertThat(HostAndPort.fromString("[::1]").requireBracketsForIPv6().getHost()).isEqualTo("::1");
    assertThat(HostAndPort.fromString("[::1]:80").requireBracketsForIPv6().getHost())
        .isEqualTo("::1");
    // Non-bracketed non-IPv6 works fine.

        .testEquals();
  }

  public void testRequireBracketsForIPv6() {
    // Bracketed IPv6 works fine.
    assertThat(HostAndPort.fromString("[::1]").requireBracketsForIPv6().getHost()).isEqualTo("::1");
    assertThat(HostAndPort.fromString("[::1]:80").requireBracketsForIPv6().getHost())
        .isEqualTo("::1");
    // Non-bracketed non-IPv6 works fine.

		{xRealIP, "[2001:db8:cafe::17]:4711", "[2001:db8:cafe::17]"},                  // IPv6 address
		{xRealIP, "", ""},                                                             // None
		{forwarded, `for="_gazonk"`, "_gazonk"},                                       // Hostname
		{forwarded, `For="[2001:db8:cafe::17]:4711`, `[2001:db8:cafe::17]`},           // IPv6 address

    if (!platform.isBouncyCastle()) {
      assertThat(recordedRequest.handshakeServerNames).containsExactly("url-host.com")
    }
  }

  /** No SNI for literal IPv6 addresses. */
  @Test
  fun ipv6() {
    val recordedRequest = requestToHostnameViaProxy("2607:f8b0:400b:804::200e")
    assertThat(recordedRequest.url.host).isEqualTo("2607:f8b0:400b:804::200e")