Fix: register ManagedFieldsEntry and FieldsV1 classes into kryo

Change-Id: I4a9f747b9b3d91a75f5f90805daf34a13726e7e0
diff --git a/apps/k8s-networking/app/src/main/java/org/onosproject/k8snetworking/impl/DistributedK8sNamespaceStore.java b/apps/k8s-networking/app/src/main/java/org/onosproject/k8snetworking/impl/DistributedK8sNamespaceStore.java
index 3df530a..1b4b6e3 100644
--- a/apps/k8s-networking/app/src/main/java/org/onosproject/k8snetworking/impl/DistributedK8sNamespaceStore.java
+++ b/apps/k8s-networking/app/src/main/java/org/onosproject/k8snetworking/impl/DistributedK8sNamespaceStore.java
@@ -16,6 +16,7 @@
 package org.onosproject.k8snetworking.impl;
 
 import com.google.common.collect.ImmutableSet;
+import io.fabric8.kubernetes.api.model.ManagedFieldsEntry;
 import io.fabric8.kubernetes.api.model.Namespace;
 import io.fabric8.kubernetes.api.model.NamespaceSpec;
 import io.fabric8.kubernetes.api.model.NamespaceStatus;
@@ -74,6 +75,7 @@
             .register(ObjectMeta.class)
             .register(NamespaceSpec.class)
             .register(NamespaceStatus.class)
+            .register(ManagedFieldsEntry.class)
             .register(LinkedHashMap.class)
             .build();