DM NodeService automatically adds aspects when properties or associations are added to a node

- AVM NodeService not covered.

git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/HEAD/root@14328 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261

source/java/org/alfresco/util/PropertyMap.java

@@ -25,7 +25,9 @@
 package org.alfresco.util;
 
 import java.io.Serializable;
+import java.util.Collections;
 import java.util.HashMap;
+import java.util.Map;
 
 import org.alfresco.service.namespace.QName;
 
@@ -41,6 +43,11 @@ public class PropertyMap extends HashMap<QName, Serializable>
 {
     private static final long serialVersionUID = 8052326301073209645L;
     
+    /**
+     * A static empty map to us when having to deal with nulls
+     */
+    public static final Map<QName, Serializable> EMPTY_MAP = Collections.<QName, Serializable>emptyMap();
+    
     /**
      * @see HashMap#HashMap(int, float)
      */