title: Problem with ZK CacheMap
body: <p>my application saves a Map , this some times made <code>JavaHeapSpace</code>  Error. 
  i used <code>org.zkoss.util.CacheMap</code> instead <a href="http://www.zkoss.org/javadoc/3.5.2/zcommon/org/zkoss/util/CacheMap.html" rel="nofollow">it's JDoc</a> </p>
  
  <p>but i am not sure if it solves the problem or not? </p>