@Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception {
        if (maxConnections > 0) {
            connections.decrementAndGet();
        }

        super.channelInactive(ctx);
    }
Closes any incoming new connections if current count is above a configured threshold.

When a connection is throttled, the channel is closed, and then a CONNECTION_THROTTLED_EVENT event is fired
not notify any other interested handlers.
zuul-core/src/main/java/com/netflix/netty/common/throttle/MaxInboundConnectionsHandler.java