Added support for a distributed set implementation that is backed by Consistent Map

Change-Id: Ic393d305d31abcdf1dd4c9afc3b9234f8d50da2d
diff --git a/core/api/src/main/java/org/onosproject/store/service/StorageService.java b/core/api/src/main/java/org/onosproject/store/service/StorageService.java
index c8a394d..e165a95 100644
--- a/core/api/src/main/java/org/onosproject/store/service/StorageService.java
+++ b/core/api/src/main/java/org/onosproject/store/service/StorageService.java
@@ -52,4 +52,12 @@
      * @return builder for an eventually consistent map
      */
     <K, V> ConsistentMapBuilder<K, V> consistentMapBuilder();
+
+    /**
+     * Creates a new distributed set builder.
+     *
+     * @param <E> set element type
+     * @return builder for an distributed set
+     */
+    <E> SetBuilder<E> setBuilder();
 }
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