private InetSocketAddress localAddress(Channel channel) {
        SocketAddress localSocketAddress = channel.localAddress();
        if (localSocketAddress != null && InetSocketAddress.class.isAssignableFrom(localSocketAddress.getClass())) {
            InetSocketAddress inetSocketAddress = (InetSocketAddress) localSocketAddress;
            if (inetSocketAddress.getAddress() != null) {
                return inetSocketAddress;
            }
        }
        return null;
    }
Returns the String form of a socket address, or {@code null} if there isn't one.
zuul-core/src/main/java/com/netflix/netty/common/SourceAddressChannelHandler.java