[VOL-4065] Fix race condition between mastership and local leadership

Change-Id: I265ea449355a5e74a43f03ca9416e31b9df84060
diff --git a/app/src/main/java/org/opencord/igmpproxy/impl/IgmpLeadershipManager.java b/app/src/main/java/org/opencord/igmpproxy/impl/IgmpLeadershipManager.java
index c40bca2..b31091b 100644
--- a/app/src/main/java/org/opencord/igmpproxy/impl/IgmpLeadershipManager.java
+++ b/app/src/main/java/org/opencord/igmpproxy/impl/IgmpLeadershipManager.java
@@ -58,17 +58,25 @@
         log.info("Stopped.");
     }
 
+    /**
+     * Checks for mastership or falls back to leadership on deviceId.
+     * If the device is available use mastership,
+     * otherwise fallback on leadership.
+     * Leadership on the device topic is needed because the master can be NONE
+     * in case the device went away, we still need to handle events
+     * consistently
+     */
     @Override
     public boolean isLocalLeader(DeviceId deviceId) {
-        if (!mastershipService.isLocalMaster(deviceId)) {
-            if (deviceService.isAvailable(deviceId)) {
-                return false;
-            }
+        if (deviceService.isAvailable(deviceId)) {
+            return mastershipService.isLocalMaster(deviceId);
+        } else {
+            // Fallback with Leadership service - device id is used as topic
             NodeId leader = leadershipService.runForLeadership(
                     deviceId.toString()).leaderNodeId();
+            // Verify if this node is the leader
             return clusterService.getLocalNode().id().equals(leader);
         }
-        return true;
     }
 
     @Override