Add distributed lock primitive

Change-Id: I60f4581d5acb5fc9b9a21d4191874bb56348af58
diff --git a/core/api/src/test/java/org/onosproject/store/service/StorageServiceAdapter.java b/core/api/src/test/java/org/onosproject/store/service/StorageServiceAdapter.java
index 14850ce..4d528e2 100644
--- a/core/api/src/test/java/org/onosproject/store/service/StorageServiceAdapter.java
+++ b/core/api/src/test/java/org/onosproject/store/service/StorageServiceAdapter.java
@@ -60,6 +60,11 @@
     }
 
     @Override
+    public DistributedLockBuilder lockBuilder() {
+        return null;
+    }
+
+    @Override
     public LeaderElectorBuilder leaderElectorBuilder() {
         return null;
     }