here an update on my topic.
I could solve the problem.
I created a new Project without App Engine. Now the persistence.xml gets used like expected.
App Engine caused, that datanucleus instead of hibernate were used.
You received this message because you are subscribed to the Google Groups "Google Web Toolkit" group.
To view this discussion on the web visit https://groups.google.com/d/msg/google-web-toolkit/-/yvYxiIy09IwJ.
To post to this group, send email to firstname.lastname@example.org.
To unsubscribe from this group, send email to email@example.com.
For more options, visit this group at http://groups.google.com/group/google-web-toolkit?hl=en.