IllegalAccessError with a Scala-based ChannelInitializer

```
java.lang.IllegalAccessError: tried to access class
io.netty.channel.ChannelPropertyAccess"... from a ChannelInitializer
when SocketChannel.pipeline() is called.
```

Perhaps a bug in Scala compiler, but we need to see if there's a workaround that can be done from our side until it is fixed.
