title: collection sorting
body: <p>The GDK docs indicate that <a href="http://groovy.codehaus.org/groovy-jdk/java/util/Collection.html#sort%28java.util.Comparator%29" rel="nofollow">Collection.sort(Comparator comparator)</a> does not change the collection it is called on, but the code below indicates otherwise. Is this a bug in the implementation, error in the docs, or a misunderstanding on my part?</p>
  
  <pre><code>class ISO3LangComparator implements Comparator&lt;Locale&gt; {
  
      int compare(Locale locale1, Locale locale2) {
          locale1.ISO3Language &lt;=&gt; locale2.ISO3Language
      }
  }
  
  List&lt;Locale&gt; locales = [Locale.FRENCH, Locale.ENGLISH]
  def sortedLocales = locales.sort(new ISO3LangComparator())
  
  // This assertion fails
  assert locales[0] == frenchLocale
  </code></pre>