title: X cannot be added because it is already mapped to the entities. X entity class and the entity is not in current project source
body: <p>I'm creating a new NetBeans EE Enterprise Application, and when I try to create Entity classes from database (Customer from the sample database), I can't select it because of this error :</p>
  
  <p><img src="https://i.stack.imgur.com/K7LSk.png" alt="enter image description here"></p>
  
  <p>Any idea? I'm using NetBeans 7.3 with Glassfish 3.1.2.</p>