README.rdoc in group_cache_key-0.2.0 vs README.rdoc in group_cache_key-0.3.0

@@ -14,9 +14,14 @@
 
     'widgets/100-81dc9bdb52d04dc20036dbd8313ed055-1256853629-1256853637'
     
 The resulting cache_key will be different if your group is sorted differently because 
 the MD5 hash is created according to the order given: no sorting is done to create the hash.
+    
+If your collection is empty, the cache_key will return a key with the object_id. A 
+cache_key for an empty collection will look like:
+
+    'empty/13149280'
 
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 == Note on Patches/Pull Requests