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I am using the relatively new Google Cloud Tools Plugin for Eclipse, replacing the Google Plugin for Eclipse. I have converted my App Engine project to the environment of the new plugin, but now the app stopped working.
I get the following error when requesting a servlet that uses a Google DataStore entry:
javax.jdo.JDOUserException: Persistent class \"Class
CLASSNAME does not seem to have been enhanced. You may want to rerun
the enhancer and check for errors in the output.\" has no table in the
database, but the operation requires it. Please check the specification
of the MetaData for this class.
The GPE (Google Plugin Eclipse) had some options for this: https://developers.google.com/eclipse/docs/appengine_orm and https://developers.google.com/eclipse/docs/appengine_datanucleus.
Unfortunately there are no settings for this in the new plugin. I tried to add the DataNucleus Plugin for Eclipse, but then I get the error: Error: Could not find or load main class org.datanucleus.enhancer.DataNucleusEnhancer, when it tries to enhance the classes.
I already tried this too: https://cloud.google.com/appengine/docs/standard/java/datastore/jdo/overview-dn2#Enhancing_Data_Classes, but I don't get how to use this with the new plugin.
I use all the latest versions of Google Cloud (App Engine SDK 1.9.50).
Any help is greatly appreciated!

The new Cloud Tools for Eclipse plugin does not support Datanucleus, the recommended way is to use the Datanucleus Maven plugin to do enhancing: http://www.datanucleus.org/products/datanucleus/jdo/enhancer.html#maven