v-leaflet can not find its Widgetset

we had one vaadin 7 application and we migrate that application to vaadin 8. but most of the component still use com.vaadin.v7… packages.
we want to use v-leaflet(vaadin 8 compatible) addons. We also use gradle and inside gradle we have vaadinCompile task with special vaadin widgetset like: (widgetset = ‘de.company.view.myWidgetset’).
I also added @widgetset(“com.vaadin.v7.Vaadin7WidgetSet”) to my mainUIClass, but in the webapplication we get this error message:
“Widgetset com.vaadin.v7.Vaadin7WidgetSet does not contain an implementation for org.vaadin.addon.leaflet.LMap.”
can anyone help me to solve this problem?