title: How do I correctly split up Google App Engine project which uses JPA into a multi-module Maven setup
body: <p>I have a project for Google App Engine which uses JPA/Datanucleus to access some Entities. That works fine so far.</p>
  
  <p>Now I would like to extract the JPA Entities into a base project in order to re-use the classes in other maven projects to avoid code-duplication.</p>
  
  <p>However when I move the sources into a base project and do the enhancement there with the maven-datanucleus-plugin, running the local app engine server fails with Exceptions like</p>
  
  <pre><code>NoPersistenceInformationException: The class "x.y.z" is required to be persistable yet no Meta-Data/Annotations can be found for this class. Please check that the Meta-Data/annotations is defined in a valid file location.
  </code></pre>
  
  <p>I have verified that enhancement seems to be fine, I see </p>
  
  <pre><code>DataNucleus Enhancer completed with success for 2 classes
  </code></pre>
  
  <p>however the directory target/generated-sources/annotations is empty, should I be seeing anything in there?</p>
  
  <p>Is it possible to separate the JPA classes into a separate maven project? Or do I need to set up my projects differently?</p>
  
  <p>And how can I verify on the class-files if they are actually enhanced or not?</p>