title: Unable to debug Eclipse Application because of missing classes
body: <p>I have written an DSL plug-in using Xtext 2.2.1. After upgrading to Xtext 2.3.0, I cannot debug the related Eclipse Application (i.e. I'm using a launch config which is labeled "Eclipse Application" to start an instance with my DSL plug-in from within Eclipse) because of this error:</p>
  
  <pre><code>Error instantiating builder 'org.eclipse.xtext.ui.shared.xtextBuilder'.
  Plug-in org.eclipse.xtext.ui.shared was unable to load class org.eclipse.xtext.ui.shared.internal.ExecutableExtensionFactory.
  org/eclipse/xtext/ui/guice/AbstractGuiceAwareExecutableExtensionFactory
  </code></pre>
  
  <p>What I tried:</p>
  
  <ol>
  <li><p>I deselected all bundles from the target platform in the launch configuration, clicked "Add Required Plug-ins", tried again, same error.</p></li>
  <li><p>I made sure that <code>org.eclipse.xtext.ui</code> and <code>org.eclipse.xtext.ui.shared</code> version <code>2.3.0</code> are available in the plug-ins list and both are enabled.</p></li>
  <li><p>When I install the plug-in into my IDE, it works perfectly. I just can't launch an Eclipse Application from within the IDE.</p></li>
  </ol>
  
  <p>"Validate Plug-ins" doesn't show any problems.</p>
  
  <p>Any ideas how I can fix this?</p>