title: Enhancing openJPA classes in Eclipse
body: <p>I'm trying to enhance openJPA classes by this guide: <a href="http://openjpa.apache.org/enhancement-with-eclipse.html" rel="nofollow">enhancement-with-eclipse.html</a></p>
  
  <p>For some reason the same setup works in Windows but gives this problem in Ubuntu. </p>
  
  <p>Does anyone see what I'm doing wrong? I've added the persistence.xml to buildpath. I've followed the guide but I still end up with this exception:</p>
  
  <pre><code> [openjpac] &lt;openjpa-2.1.0-r422266:1071316 fatal user error&gt; org.apache.openjpa.util.MetaDataException: MetaDataFactory could not be configured (conf.newMetaDataFactoryInstance() returned null). This might mean that no configuration properties were found. Ensure that you have a META-INF/persistence.xml file, that it is available in your classpath, or that the properties file you are using for configuration is available. If you are using Ant, please see the &lt;properties&gt; or &lt;propertiesFile&gt; attributes of the task's nested &lt;config&gt; element. This can also occur if your OpenJPA distribution jars are corrupt, or if your security policy is overly strict.
  [openjpac]  at org.apache.openjpa.meta.MetaDataRepository.initializeMetaDataFactory(MetaDataRepository.java:1904)
  [openjpac]  at org.apache.openjpa.meta.MetaDataRepository.endConfiguration(MetaDataRepository.java:1885)
  [openjpac]  at org.apache.openjpa.lib.conf.Configurations.configureInstance(Configurations.java:518)
  [openjpac]  at org.apache.openjpa.lib.conf.Configurations.configureInstance(Configurations.java:443)
  [openjpac]  at org.apache.openjpa.lib.conf.PluginValue.instantiate(PluginValue.java:104)
  [openjpac]  at org.apache.openjpa.conf.MetaDataRepositoryValue.instantiate(MetaDataRepositoryValue.java:68)
  [openjpac]  at org.apache.openjpa.lib.conf.ObjectValue.instantiate(ObjectValue.java:83)
  [openjpac]  at org.apache.openjpa.conf.OpenJPAConfigurationImpl.newMetaDataRepositoryInstance(OpenJPAConfigurationImpl.java:949)
  [openjpac]  at org.apache.openjpa.ant.PCEnhancerTask.executeOn(PCEnhancerTask.java:88)
  [openjpac]  at org.apache.openjpa.lib.ant.AbstractTask.execute(AbstractTask.java:171)
  [openjpac]  at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291)
  [openjpac]  at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
  [openjpac]  at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
  [openjpac]  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  [openjpac]  at java.lang.reflect.Method.invoke(Method.java:616)
  [openjpac]  at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
  [openjpac]  at org.apache.tools.ant.Task.perform(Task.java:348)
  [openjpac]  at org.apache.tools.ant.Target.execute(Target.java:390)
  [openjpac]  at org.apache.tools.ant.Target.performTasks(Target.java:411)
  [openjpac]  at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1360)
  [openjpac]  at org.apache.tools.ant.Project.executeTarget(Project.java:1329)
  [openjpac]  at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:41)
  [openjpac]  at org.eclipse.ant.internal.core.ant.EclipseDefaultExecutor.executeTargets(EclipseDefaultExecutor.java:32)
  [openjpac]  at org.apache.tools.ant.Project.executeTargets(Project.java:1212)
  [openjpac]  at org.eclipse.ant.internal.core.ant.InternalAntRunner.run(InternalAntRunner.java:662)
  [openjpac]  at org.eclipse.ant.internal.core.ant.InternalAntRunner.run(InternalAntRunner.java:495)
  [openjpac]  at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
  [openjpac]  at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
  [openjpac]  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  [openjpac]  at java.lang.reflect.Method.invoke(Method.java:616)
  [openjpac]  at org.eclipse.ant.core.AntRunner.run(AntRunner.java:378)
  [openjpac]  at org.eclipse.ant.internal.ui.launchConfigurations.AntLaunchDelegate.runInSameVM(AntLaunchDelegate.java:277)
  [openjpac]  at org.eclipse.ant.internal.ui.launchConfigurations.AntLaunchDelegate.launch(AntLaunchDelegate.java:239)
  [openjpac]  at org.eclipse.debug.internal.core.LaunchConfiguration.launch(LaunchConfiguration.java:853)
  [openjpac]  at org.eclipse.debug.internal.core.LaunchConfiguration.launch(LaunchConfiguration.java:703)
  [openjpac]  at org.eclipse.debug.internal.core.LaunchConfiguration.launch(LaunchConfiguration.java:696)
  [openjpac]  at org.eclipse.ui.externaltools.internal.model.ExternalToolBuilder.launchBuild(ExternalToolBuilder.java:179)
  [openjpac]  at org.eclipse.ui.externaltools.internal.model.ExternalToolBuilder.doBuildBasedOnScope(ExternalToolBuilder.java:167)
  [openjpac]  at org.eclipse.ui.externaltools.internal.model.ExternalToolBuilder.build(ExternalToolBuilder.java:86)
  [openjpac]  at org.eclipse.core.internal.events.BuildManager$2.run(BuildManager.java:627)
  [openjpac]  at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
  [openjpac]  at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:170)
  [openjpac]  at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:201)
  [openjpac]  at org.eclipse.core.internal.events.BuildManager$1.run(BuildManager.java:253)
  [openjpac]  at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
  [openjpac]  at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:256)
  [openjpac]  at org.eclipse.core.internal.events.BuildManager.basicBuildLoop(BuildManager.java:309)
  [openjpac]  at org.eclipse.core.internal.events.BuildManager.build(BuildManager.java:341)
  [openjpac]  at org.eclipse.core.internal.resources.Workspace.build(Workspace.java:330)
  [openjpac]  at org.eclipse.ui.actions.GlobalBuildAction$1.run(GlobalBuildAction.java:178)
  [openjpac]  at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55)
  </code></pre>
  
  <p>ALL HELP GREATLY APPRECIATED!</p>