title: NoClassDefFoundError PlexusIoResourceCollection / Jenkins + Maven 3
body: <p>i'm trying to migrate some of my jenkins jobs to maven 3 and i'm facing some troubles with maven plugins.</p>
  
  <p>for instance, i have a job building pretty well under maven 2, which fires the following exception when i move to maven 3</p>
  
  <pre><code>WARNING: Error injecting: org.apache.maven.plugin.jar.JarMojo
      java.lang.NoClassDefFoundError: org/codehaus/plexus/components/io/resources/PlexusIoResourceCollection
  .
  .
  .
      Caused by: java.lang.ClassNotFoundException: org.codehaus.plexus.components.io.resources.PlexusIoResourceCollection
          at org.codehaus.plexus.classworlds.strategy.SelfFirstStrategy.loadClass(SelfFirstStrategy.java:50)
          at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:244)
          at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:230)
          ... 93 more
      mojoFailed org.apache.maven.plugins:maven-jar-plugin:2.3.2(default-jar)
  </code></pre>
  
  <p>I ckecked that the required class was correctly installed to my local repository. Does anyone have a clue about this behavior ?</p>
  
  <p>thanks in advance.</p>