code: public void removeHandlers() {
      Iterator<HandlerRegistration> it = registrations.iterator();
      while (it.hasNext()) {
        HandlerRegistration r = it.next();
  
        /*
         * must remove before we call removeHandler. Might have come from nested
         * ResettableEventBus
         */
        it.remove();
  
        r.removeHandler();
      }
    }
docs: Remove all handlers that have been added through this wrapper.