title: Checkstyle Eclipse plugin doesn't work
body: <p>I'm using eclipse checkstyle plugin with Juno Eclipse distribution. Anytime the code is checked for checkstyle error I get the following error: </p>
  
  <pre><code>cannot initialize module TreeWalker - Unable to instantiate DoubleCheckedLocking
  </code></pre>
  
  <p>Does anybody know how to fix this problem? Is it a plugin compatibility issue or something else?</p>