title: maven-processor-plugin to ignore undefined symbols
body: <p>I've JPA 2 maven project and I want to process sources to have the static meta model. What I did I took <a href="http://docs.jboss.org/hibernate/stable/orm/topical/html/metamodelgen/MetamodelGenerator.html" rel="nofollow">JBoss' static meta model processor</a> and set it up to run during <code>generate-sources</code> phase. Now, obviously I have some classes that reference the meta model and compilation itself goes fine. But <code>maven-processor-plugin</code> itself generates errors complaining that it can't find symbols from meta model like this:</p>
  
  <pre><code>[INFO] --- maven-processor-plugin:2.2.4:process (process) @ ng-grid-java ---
  [ERROR] diagnostic: c:\...\service\position\PositionSpecifications.java:13: cannot find symbol
  symbol  : class Position_
  </code></pre>
  
  <p>Which is logical because it actually generates these classes, but is not right since it brings errors to an otherwise correct project. Or maybe I'm using it wrong? Am I missing something?</p>
  
  <p><strong>Update:</strong> I have been able to inhibit the error output by using configuration parameter <code>outputDiagnostics</code> but I'm not sure that's the right way.</p>