I've taken a look at what's left to clear up checkstyle.     Our errors boil down to a few categories - I don't mind going through and fixing them if that's what we want, but if not, it'd probably be helpful to comment out the rules to clear out the noise :

Checkstyle rule "DesignForExtension" :

Code example :

Service Registration.java,

ServiceRegistration(QName serviceName,
            Endpoint endpoint,
            HandlerChain handlers,
            ServiceRegistry registry,
            ServiceDomain domain) {

        _serviceName = serviceName;
        _endpoint = endpoint;
        _handlers = handlers;
        _registry = registry;
        _domain = domain;
    }

all of the parameters get the error that they should be final.     We discussed this rule on a call and I don't believe we came to any conclusion about what to do about it.

Checkstyle rule "FinalLocalVariable" :
Code example :

ServiceRegistration.java

public ServiceDomain getDomain() {
        return _domain;
    }

    @Override
    public QName getName() {
        return _serviceName;
    }

both methods get the error that they are not designed for extension and that they need to be abstract, final or empty.      I believe we discussed this rule on one of the calls and decided to scrap it but I wanted to double check before submitting a pull request with it.