serialization related fixes for flow related classes

Change-Id: Id7e1241cc73645bd87b61eac4ca45acd35ad22ca

@@ -8,7 +8,6 @@ import org.onlab.packet.IpPrefix;
 import org.onlab.packet.MacAddress;
 import org.onlab.packet.VlanId;
 
-import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Objects;
@@ -27,7 +26,7 @@ public final class DefaultTrafficSelector implements TrafficSelector {
      * @param criteria criteria
      */
     private DefaultTrafficSelector(Set<Criterion> criteria) {
-        this.criteria = Collections.unmodifiableSet(criteria);
+        this.criteria = ImmutableSet.copyOf(criteria);
     }
 
     @Override

@@ -7,7 +7,8 @@ import org.onlab.packet.IpPrefix;
 import org.onlab.packet.MacAddress;
 import org.onlab.packet.VlanId;
 
-import java.util.Collections;
+import com.google.common.collect.ImmutableList;
+
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Objects;
@@ -25,7 +26,7 @@ public final class DefaultTrafficTreatment implements TrafficTreatment {
      * @param instructions treatment instructions
      */
     private DefaultTrafficTreatment(List<Instruction> instructions) {
-        this.instructions = Collections.unmodifiableList(instructions);
+        this.instructions = ImmutableList.copyOf(instructions);
     }
 
     @Override

@@ -26,6 +26,7 @@ import org.onlab.onos.net.PortNumber;
 import org.onlab.onos.net.device.DefaultDeviceDescription;
 import org.onlab.onos.net.device.DefaultPortDescription;
 import org.onlab.onos.net.flow.DefaultFlowRule;
+import org.onlab.onos.net.flow.DefaultTrafficSelector;
 import org.onlab.onos.net.flow.FlowId;
 import org.onlab.onos.net.host.DefaultHostDescription;
 import org.onlab.onos.net.host.HostDescription;
@@ -88,7 +89,8 @@ public final class KryoNamespaces {
                     HostDescription.class,
                     DefaultHostDescription.class,
                     DefaultFlowRule.class,
-                    FlowId.class
+                    FlowId.class,
+                    DefaultTrafficSelector.class
                     )
             .register(URI.class, new URISerializer())
             .register(NodeId.class, new NodeIdSerializer())