Bug fixes for ONOS-3509

- Forwarding behavior added to {Device,Link}Store by ONOS-490
  cauesed false update information sent from ONOS node, which has been detached from the cluster,
  to be accepted by rest of the cluster after the detached node has rejoined cluster.

- Fix for periodic mastership check was left out
  when MastershipService#requestRoleFor(..) return value was changed to Future.

- Fix for triggerProbe() related messages getting dropped,
  right after STANDBY -> MASTER role change.

- Local state (connectedDevices) was preventing
  vertical (Core -> switch) Mastership state synchronization.

- Various debug log, comment added during investigation.

Change-Id: I777beadf04db8a879830a07bfdc7ab0e2279f190
diff --git a/core/store/dist/src/main/java/org/onosproject/store/cluster/impl/DistributedClusterStore.java b/core/store/dist/src/main/java/org/onosproject/store/cluster/impl/DistributedClusterStore.java
index 3bb6a70..b2ee832 100644
--- a/core/store/dist/src/main/java/org/onosproject/store/cluster/impl/DistributedClusterStore.java
+++ b/core/store/dist/src/main/java/org/onosproject/store/cluster/impl/DistributedClusterStore.java
@@ -15,6 +15,7 @@
  */
 package org.onosproject.store.cluster.impl;
 
+import com.google.common.base.MoreObjects;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Maps;
 
@@ -163,7 +164,7 @@
     @Override
     public State getState(NodeId nodeId) {
         checkNotNull(nodeId, INSTANCE_ID_NULL);
-        return nodeStates.get(nodeId);
+        return MoreObjects.firstNonNull(nodeStates.get(nodeId), State.INACTIVE);
     }
 
     @Override