In https://github.com/jboss-jdf/jboss-as-quickstart/blob/master/helloworld-html5/src/main/webapp/WEB-INF/web.xml :

<!-- One of the way of activating REST Servises is adding these lines, the server is responsible for adding the corresponding servlet automatically. If the src folder, org.jboss.as.quickstarts.html5restoWorld class has the Annotations to receive REST invocation-->

I think something important got hidden by this