DeviceManager queries MastershipService

Change-Id: I0d391ecb7f0b1e4cced99cfe8083b46f74ee35bb
diff --git a/core/net/src/main/java/org/onlab/onos/cluster/impl/MastershipManager.java b/core/net/src/main/java/org/onlab/onos/cluster/impl/MastershipManager.java
index 492f0d4..ab27dc3 100644
--- a/core/net/src/main/java/org/onlab/onos/cluster/impl/MastershipManager.java
+++ b/core/net/src/main/java/org/onlab/onos/cluster/impl/MastershipManager.java
@@ -65,7 +65,10 @@
         checkNotNull(nodeId, NODE_ID_NULL);
         checkNotNull(deviceId, DEVICE_ID_NULL);
         checkNotNull(role, ROLE_NULL);
-        store.setRole(nodeId, deviceId, role);
+        MastershipEvent event = store.setRole(nodeId, deviceId, role);
+        if (event != null) {
+            post(event);
+        }
     }
 
     @Override