Add atomic mastership/term/backups method to MastershipService

Change-Id: I18c3aeaa5101c9ce08ff38fffd70eaec903a0f3e
diff --git a/core/api/src/main/java/org/onosproject/mastership/MastershipService.java b/core/api/src/main/java/org/onosproject/mastership/MastershipService.java
index 86042b0..a5a0c43 100644
--- a/core/api/src/main/java/org/onosproject/mastership/MastershipService.java
+++ b/core/api/src/main/java/org/onosproject/mastership/MastershipService.java
@@ -120,6 +120,14 @@
     RoleInfo getNodesFor(DeviceId deviceId);
 
     /**
+     * Returns the mastership info for the given device.
+     *
+     * @param deviceId the device for which to return the mastership info
+     * @return the mastership info for the given device
+     */
+    MastershipInfo getMastershipFor(DeviceId deviceId);
+
+    /**
      * Returns the devices for which a controller is master.
      * <p>
      * Returned Set may contain DeviceId which no longer exist in the system.