--- old/src/share/classes/java/util/WeakHashMap.java	2012-05-03 14:15:25.082395544 +0800
+++ new/src/share/classes/java/util/WeakHashMap.java	2012-05-03 14:15:24.830394288 +0800
@@ -94,7 +94,10 @@
  * to deal with this is to wrap values themselves within
  * <tt>WeakReferences</tt> before
  * inserting, as in: <tt>m.put(key, new WeakReference(value))</tt>,
- * and then unwrapping upon each <tt>get</tt>.
+ * and then unwrapping upon each <tt>get</tt>. However, as the use of
+ * <tt>WeakReference</tt> in this manner will not prevent value objects
+ * from being GC'd, this approach is only useful when entries in the map
+ * are not relied upon for keeping the underlying value objects "live".
  *
  * <p>The iterators returned by the <tt>iterator</tt> method of the collections
  * returned by all of this class's "collection view methods" are