#vulnerable code 
                             public ChannelFuture asynwrite(Object msg){
		Channel ch = fetchOneWritable();
		ChannelFuture future = ch.writeAndFlush(msg);
		return future;
	} 
                            #location 3 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                             public ChannelFuture asynwrite(Object msg){
		Channel ch = fetchOneWritable();
		if(ch == null) return null;
		ChannelFuture future = ch.writeAndFlush(msg);
		return future;
	}