ModelBuildingEventCatapult catapult) {
        ModelBuildingListener listener = request.getModelBuildingListener();

        if (listener != null) {
            ModelBuildingEvent event = new DefaultModelBuildingEvent(model, request, problems);

            catapult.fire(listener, event);
        }
    }

        ModelBuildingListener listener = getModelBuildingListener(request);

        if (listener != null) {
            AtomicReference<Model> m = new AtomicReference<>(model);

            ModelBuildingEvent event = new DefaultModelBuildingEvent(model, m::set, request, problems);

            catapult.accept(listener, event);

            return m.get();
        }