Netty AttributeKey - Cannot infer type arguments for AttributeKey<>

Question

I have used this before so I have NO idea why this doesn't work. Consider this code

public class NioServer implements Runnable {

    private EventLoopGroup group;
    private ServerBootstrap b;

    public static final AttributeKey<Session> SESSION_KEY = new AttributeKey<>("SessionHandler.attr");

    @Override
    public void run() {
    group = new NioEventLoopGroup();
    b = new ServerBootstrap();
    b.group(group)
        .channel(NioServerSocketChannel.class)
        .localAddress(435)
        .childOption(ChannelOption.SO_KEEPALIVE, true)
        .childOption(ChannelOption.TCP_NODELAY, true)
        .childHandler(new ChannelInitializer<SocketChannel>() {

            @Override
            protected void initChannel(SocketChannel ch) throws Exception {
            ch.pipeline().addLast("Session Handler", new SessionHandler());
            }

        });
    }

}

The AttributeKey SESSION_KEY does not want to work and gives the error:

"cannot infer type arguments for AttributeKey<> reason: cannot infer type-variable(s) T (actual and formal argument lists differ in length) where T is a type-variable: T extends Object declared in class AttributeKey"

I don't get it... Am I missing something? There are no other questions about this however other questions do successfully use AttributeKey in this way.

Specs:

• Netty 4.1.0 - netty-all-4.1.0.Beta1.jar
• JDK 1.8

Update:

Alright so I have downgraded the version to 4.0.21 Final and apparently AttributeKey<>("") is deprecated however I cannot find any further information on this. Anyone knows the replacement/alternative for this in the 4.1.0 version? It works in 4.0.21 Final by the way.

Answer 1

Alright. Quoting the user 'Mics':

Short answer: There's no AttributeKey(String) in netty 4.1, use AttributeKey.valueOf(String). Additional information: github.com/netty/netty/issues/1824

Thanks for the answer.