avoid transient changes to MastershipStore from being posted as events

Change-Id: Id033cf50f865e44439138f5b3814ebaedb832b73
diff --git a/core/api/src/main/java/org/onlab/onos/net/device/DeviceProvider.java b/core/api/src/main/java/org/onlab/onos/net/device/DeviceProvider.java
index fff6333..8411b09 100644
--- a/core/api/src/main/java/org/onlab/onos/net/device/DeviceProvider.java
+++ b/core/api/src/main/java/org/onlab/onos/net/device/DeviceProvider.java
@@ -47,4 +47,11 @@
      */
     void roleChanged(Device device, MastershipRole newRole);
 
+    /**
+     * Checks the reachability (connectivity) of a device from this provider.
+     *
+     * @param device device to check
+     * @return true if reachable, false otherwise
+     */
+    boolean isReachable(Device device);
 }