private static boolean hasNoIpV6NetworkInterface() {
            try {
                final Enumeration<NetworkInterface> interfaces = NetworkInterface.getNetworkInterfaces();
                while (interfaces.hasMoreElements()) {
                    final NetworkInterface iface = interfaces.nextElement();
                    final Enumeration<InetAddress> addresses = iface.getInetAddresses();
                    while (addresses.hasMoreElements()) {
                        final InetAddress inetAddress = addresses.nextElement();
                        if (inetAddress instanceof Inet6Address && !inetAddress.isAnyLocalAddress() &&
                            !inetAddress.isLoopbackAddress() && !inetAddress.isLinkLocalAddress()) {
                            return false;
                        }
                    }
                }
            } catch (SocketException e) {
                logger.debug("Unable to detect if the machine has an IPv6 network interface", e);
                return false;
            }
            return true;
        }
Returns {@code true} if no {@link NetworkInterface} supports {@code IPv6}, {@code false} otherwise.
core/src/main/java/com/linecorp/armeria/common/util/SystemInfo.java