Is appengine-api-1.0-sdk-1.2.1.jar required

Is appengine-api-1.0-sdk-1.2.1.jar required for running Vaadin 7.0. There is a conflict between this package and another email package in my project. It looks like this is for Google’s cloud hosting stuff. I am not sure why we need it Vaadin.
I would like to know if it’s safe to remove this package from Vaadin project.

It is only needed for Google App Engine.
Note, though, that if your server validates that every class referenced in the WAR is available (some servers check that), it might complain.

This bit me also when upgrading from Vaadin 6 to 7. The README.TXT file states:

  1. Copy lib/*.jar to WEB-INF/lib in your project

I think it would be helpful to add additional information regarding the inclusion/exclusion of this jar.