* @return {@link Inet4Address} of embedded IPv4 client address
   * @throws IllegalArgumentException if the argument does not have a valid embedded IPv4 address
   */
  public static Inet4Address getEmbeddedIPv4ClientAddress(Inet6Address ip) {
    if (isCompatIPv4Address(ip)) {
      return getCompatIPv4Address(ip);
    }

    if (is6to4Address(ip)) {
      return get6to4IPv4Address(ip);
    }

    assertThat(InetAddresses.getEmbeddedIPv4ClientAddress(testIp)).isEqualTo(ipv4);

    // Test 6to4 address.
    testIp = (Inet6Address) InetAddresses.forString("2002:0102:0304::1");
    assertTrue(InetAddresses.hasEmbeddedIPv4ClientAddress(testIp));
    ipv4 = InetAddresses.forString("1.2.3.4");
    assertThat(InetAddresses.getEmbeddedIPv4ClientAddress(testIp)).isEqualTo(ipv4);

    // Test Teredo address.