ONOS-1438: Segment Routing rule population optimization fixes

Change-Id: I2cad2cd485282b904e035b209530005b93c90ffd
diff --git a/core/api/src/main/java/org/onosproject/net/group/Group.java b/core/api/src/main/java/org/onosproject/net/group/Group.java
index 776d24f..5440775 100644
--- a/core/api/src/main/java/org/onosproject/net/group/Group.java
+++ b/core/api/src/main/java/org/onosproject/net/group/Group.java
@@ -35,6 +35,10 @@
          */
         PENDING_ADD,
         /**
+         * Group is missing in data plane and retrying GROUP ADD request.
+         */
+        PENDING_ADD_RETRY,
+        /**
          * Group is created in the data plane.
          */
         ADDED,