Revisit Annotations merging

- avoid extra instantiation/copying when possible

Change-Id: Ia2f74a1fe2ff1176346316565c9bc6786cd7f6e4
diff --git a/core/net/src/main/java/org/onosproject/net/host/impl/BasicHostOperator.java b/core/net/src/main/java/org/onosproject/net/host/impl/BasicHostOperator.java
index dd56217..87f908a 100644
--- a/core/net/src/main/java/org/onosproject/net/host/impl/BasicHostOperator.java
+++ b/core/net/src/main/java/org/onosproject/net/host/impl/BasicHostOperator.java
@@ -80,10 +80,10 @@
      */
     public static SparseAnnotations combine(BasicHostConfig cfg, SparseAnnotations an) {
         DefaultAnnotations.Builder builder = DefaultAnnotations.builder();
-
+        builder.putAll(an);
         combineElementAnnotations(cfg, builder);
 
-        return DefaultAnnotations.union(an, builder.build());
+        return builder.build();
     }
 
     /**