code: public static Inet4Address getIsatapIPv4Address(Inet6Address ip) {
      checkArgument(isIsatapAddress(ip), "Address '%s' is not an ISATAP address.", toAddrString(ip));
  
      return getInet4Address(Arrays.copyOfRange(ip.getAddress(), 12, 16));
    }
docs: Returns the IPv4 address embedded in an ISATAP address.
  
  @param ip {@link Inet6Address} to be examined for embedded IPv4 in ISATAP address
  @return {@link Inet4Address} of embedded IPv4 in an ISATAP address
  @throws IllegalArgumentException if the argument is not a valid IPv6 ISATAP address