I'm not sure if we want to support this case or it is just a documentation error.

When adding a client and pass the callbacks in settings, as shown here: https://github.com/tolis-e/aerogear-js/blob/master/src/notifier/adapters/vertx.js#L201

then the callbacks are not propagated to the connect method:
https://github.com/tolis-e/aerogear-js/blob/master/src/notifier/adapters/vertx.js#L239