Add compatibility functions to AtomicValue/Topic

Change-Id: I4a597cfa3effe0a62714ab12440a2fc41ac58aa9
diff --git a/core/api/src/main/java/org/onosproject/store/service/PrimitiveService.java b/core/api/src/main/java/org/onosproject/store/service/PrimitiveService.java
index 7be0480..cc77393 100644
--- a/core/api/src/main/java/org/onosproject/store/service/PrimitiveService.java
+++ b/core/api/src/main/java/org/onosproject/store/service/PrimitiveService.java
@@ -114,6 +114,14 @@
     LeaderElectorBuilder leaderElectorBuilder();
 
     /**
+     * Creates a new TopicBuilder.
+     *
+     * @param <T> topic value type
+     * @return topic builder
+     */
+    <T> TopicBuilder<T> topicBuilder();
+
+    /**
      * Creates a new transaction context builder.
      *
      * @return a builder for a transaction context.