[ONOS-7239] Fix - ModArp*Instruction not serialized in KryoNamespaces

Change-Id: Ib06ec70fb4bf0d5bc7cd78e374e7481377d305a7
diff --git a/core/store/serializers/src/main/java/org/onosproject/store/serializers/KryoNamespaces.java b/core/store/serializers/src/main/java/org/onosproject/store/serializers/KryoNamespaces.java
index 6e8b25a..47bcd27 100644
--- a/core/store/serializers/src/main/java/org/onosproject/store/serializers/KryoNamespaces.java
+++ b/core/store/serializers/src/main/java/org/onosproject/store/serializers/KryoNamespaces.java
@@ -707,6 +707,10 @@
             )
             .register(Upgrade.class)
             .register(Upgrade.Status.class)
+            .register(L3ModificationInstruction.ModArpEthInstruction.class,
+                    L3ModificationInstruction.ModArpEthInstruction.class,
+                    L3ModificationInstruction.ModArpOpInstruction.class,
+                    L3ModificationInstruction.ModArpIPInstruction.class)
             .build("API");
 
     /**