ALF-10168 - DocLib doesn't correctly handle deleted users after Swift refactor

git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/HEAD/root@30222 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261

source/java/org/alfresco/repo/jscript/app/UsernamePropertyDecorator.java

@@ -69,7 +69,8 @@ public class UsernamePropertyDecorator implements PropertyDecorator
         }
         else
         {
-            return null;
+            map.put("isDeleted", true);
+            return (Serializable)map;
         }
 
         map.put("firstName", firstName);