public static Handler fromClassName(String className) {
        return new Handler(new ComponentModel(className, null, null, null));
    }
Models a jdisc RequestHandler (including ClientProvider).
RequestHandlers always have at least one server binding,
while ClientProviders have at least one client binding.

@author gjoranv
config-model/src/main/java/com/yahoo/vespa/model/container/component/Handler.java