Add distributed lock primitive

Change-Id: I60f4581d5acb5fc9b9a21d4191874bb56348af58
diff --git a/core/store/primitives/src/main/java/org/onosproject/store/primitives/impl/StorageManager.java b/core/store/primitives/src/main/java/org/onosproject/store/primitives/impl/StorageManager.java
index 2474d74..de3229f 100644
--- a/core/store/primitives/src/main/java/org/onosproject/store/primitives/impl/StorageManager.java
+++ b/core/store/primitives/src/main/java/org/onosproject/store/primitives/impl/StorageManager.java
@@ -47,6 +47,7 @@
 import org.onosproject.store.service.ConsistentMapBuilder;
 import org.onosproject.store.service.ConsistentMultimapBuilder;
 import org.onosproject.store.service.ConsistentTreeMapBuilder;
+import org.onosproject.store.service.DistributedLockBuilder;
 import org.onosproject.store.service.DistributedSetBuilder;
 import org.onosproject.store.service.DocumentTreeBuilder;
 import org.onosproject.store.service.EventuallyConsistentMapBuilder;
@@ -236,6 +237,12 @@
     }
 
     @Override
+    public DistributedLockBuilder lockBuilder() {
+        checkPermission(STORAGE_WRITE);
+        return new DefaultDistributedLockBuilder(federatedPrimitiveCreator);
+    }
+
+    @Override
     public LeaderElectorBuilder leaderElectorBuilder() {
         checkPermission(STORAGE_WRITE);
         return new DefaultLeaderElectorBuilder(federatedPrimitiveCreator);