title: Add persistent attribute to live JDO class. (App Engine)
body: <p>How can I add a new <code>@Persistent</code> attribute to a class that gets stored on App Engine as JDO (Similar to adding a new column to a relational live database table)? When I add a new attribute I get the exception:</p>
  
  <blockquote>
    <p>java.lang.RuntimeException:
    com.google.gwt.user.client.rpc.IncompatibleRemoteServiceException: The
    response could not be deserialized</p>
  </blockquote>