ONOS-944: Implemented a Group operation failure handler in GroupManger and SimpleGroupStore.

Change-Id: Ib3be4d534ceff04af2dad0c062fd4cd63d49ee82
diff --git a/core/api/src/main/java/org/onosproject/net/group/GroupStore.java b/core/api/src/main/java/org/onosproject/net/group/GroupStore.java
index 2fc7030..6803b58 100644
--- a/core/api/src/main/java/org/onosproject/net/group/GroupStore.java
+++ b/core/api/src/main/java/org/onosproject/net/group/GroupStore.java
@@ -143,4 +143,12 @@
      * @return initial group audit status
      */
     boolean deviceInitialAuditStatus(DeviceId deviceId);
+
+    /**
+     * Indicates the group operations failed.
+     *
+     * @param deviceId the device ID
+     * @param operation the group operation failed
+     */
+    void groupOperationFailed(DeviceId deviceId, GroupOperation operation);
 }