In netty-4.1.28.Final version, an error occurs when running on jdk6.

[koo-taejin]

Actual behavior

io.netty.channel.ChannelException: Unable to create Channel from class class io.netty.channel.socket.nio.NioSocketChannel
Caused by: java.lang.NoClassDefFoundError: java/nio/channels/NetworkChannel
	at io.netty.channel.socket.nio.NioSocketChannel.<init>(NioSocketChannel.java:105)
	at io.netty.channel.socket.nio.NioSocketChannel.<init>(NioSocketChannel.java:94)
	at io.netty.channel.socket.nio.NioSocketChannel.<init>(NioSocketChannel.java:87)
	at io.netty.channel.socket.nio.NioSocketChannel.<init>(NioSocketChannel.java:80)
	... 32 more
Caused by: java.lang.ClassNotFoundException: java.nio.channels.NetworkChannel
	at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:247)

Steps to reproduce

// run following test on jvm6

    @Test
    public void listenerTest() throws Exception {
        Bootstrap bootstrap = createBootstrap();
        Channel channel = bootstrap.connect(host, port).sync().channel();

    }

    public Bootstrap createBootstrap() {
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        Bootstrap bootstrap = new Bootstrap();
        bootstrap.group(workerGroup).channel(NioSocketChannel.class)
                .handler(new ChannelInitializer<SocketChannel>() {
                    @Override
                    protected void initChannel(SocketChannel ch) throws Exception {
                        ch.pipeline().addLast(new HttpClientCodec());
                        ch.pipeline().addLast(new HttpObjectAggregator(65535));
                    }
                });
        return bootstrap;
    }

Netty version

netty-4.1.28.Final

JVM version (e.g. java -version)

1.6.0_45

OS version (e.g. uname -a)

Windows10, CentOS 6.6

I think this issue is problem, but I'm not sure.
If this issue is problem, May I make a correction?

[normanmaurer]

@koo-taejin PTAL #8168