public static ChannelFuture flush(Channel channel) {
        ChannelFuture future = future(channel);
        channel.getPipeline().sendDownstream(
                new DownstreamFlushEvent(channel, future));
        return future;
    }
public static ChannelFuture flush ( Channel channel ) { ChannelFuture future = future ( channel ) ; channel . getPipeline ( ) . sendDownstream ( new DownstreamFlushEvent ( channel , future ) ) ; return future ; }
Sends a {@code "flush"} request to the last
{@link ChannelDownstreamHandler} in the {@link ChannelPipeline} of
the specified {@link Channel}.

@param channel  the channel to bind

@return the {@link ChannelFuture} which will be notified when the
flush operation is done