public static void removeHandlerFromPipeline(String handlerName, ChannelPipeline pipeline) {
        if (pipeline.get(handlerName) != null) {
            pipeline.remove(handlerName);
        }
    }
Gracefully shuts down a DefaultClientChannelManager by allowing in-flight requests to finish before closing the connections.
Idle connections in the connection pools are closed, and any connections associated with an in-flight request
will be closed upon trying to return the connection to the pool
zuul-core/src/main/java/com/netflix/zuul/netty/connectionpool/DefaultClientChannelManager.java