Java Vaadin Designer for Vaadin 8
JaVaDe 8 is the latest version of JaVaDe. It's a migration of the original JaVaDe to Vaadin 8 and should be used only with it. The designer preview and the generated code are for Vaadin 8, the application still depends on Vaadin 7 and in order to work you need to add the compatibility jars (already included in the Dependencies archive).
You cannot import projects from JaVaDe 7. The MongoDB repository is always with name ending in 8. You can still start the server with -Djavade.properties=(...).