assertThrows(IllegalArgumentException.class, () -> InetAddresses.increment(address_ffffff));
  }

  @SuppressWarnings("IdentifierName") // the best we could do for adjacent digit blocks
  public void testIncrementIPv6() throws UnknownHostException {
    InetAddress addressV6_66_0 = InetAddress.getByName("2001:db8::6600");
    InetAddress addressV6_66_ff = InetAddress.getByName("2001:db8::66ff");