title: Platform.getBundle returns null
body: <p>I have an eclipse plugin and have learned that I can retrieve a workspace-dependent bundle path for that like this:</p>
  
  <pre><code>Bundle bundle = FrameworkUtil.getBundle(getClass());
  IPath path = Platform.getStateLocation(bundle);
  </code></pre>
  
  <p>If I put that code into the start-method of my Bundle activator class everything works fine. But I would need the path in another class within my plugin.</p>
  
  <p>Now, I tried to do get the 'Bundle' like this:</p>
  
  <pre><code>    bundleID = "de.some.thing.plugin" // ID of that plugin like in plugin.xml
      Bundle bundle = Platform.getBundle(bundleID);
      ...
  </code></pre>
  
  <p>But this returns null. Can anybody help me troubleshooting or understanding why it does not work?</p>