private static boolean isIpV6(String ipAddr) {
        return ipAddr.indexOf(':') >= 0;
    }
Returns the {@link StandardProtocolFamily} of this endpoint's IP address.

@return the {@link StandardProtocolFamily} of this endpoint's IP address, or
        {@code null} if the host name is not resolved yet.
core/src/main/java/com/linecorp/armeria/client/Endpoint.java