'fixes' an issue where you can get any property value back due to the incorrect cache key being used

src/Umbraco.Core/Collections/CompositeStringStringKey.cs

@@ -20,7 +20,11 @@ namespace Umbraco.Core.Collections
         public CompositeStringStringKey(string key1, string key2)
         {
             _key1 = key1?.ToLowerInvariant() ?? "NULL";
-            _key2 = key2?.ToLowerInvariant() ?? "NULL";
+
+            //fixme - we are changing this to null if it is an empty string, this is because if we don't do this than this key will not match
+            // anything see comments http://issues.umbraco.org/issue/U4-11227#comment=67-46399
+            // since we're not dealing with segments right now and I just need to get something working, this is the 'fix'
+            _key2 = !key2.IsNullOrWhiteSpace() ? key2.ToLowerInvariant() : "NULL";
         }
 
         public bool Equals(CompositeStringStringKey other)