switch to ImmutableList

Change-Id: Ia5f8936d0aaf447253f5dde0db1ee688441d2472

 package org.onlab.onos.cluster;
 
-import java.util.Collections;
 import java.util.List;
 import java.util.Objects;
 
+import com.google.common.collect.ImmutableList;
+
 /**
  * A container for detailed role information for a device,
  * within the current cluster. Role attributes include current
@@ -15,7 +16,7 @@ public class RoleInfo {
 
     public RoleInfo(NodeId master, List<NodeId> backups) {
         this.master = master;
-        this.backups = Collections.unmodifiableList(backups);
+        this.backups = ImmutableList.copyOf(backups);
     }
 
     public NodeId master() {

@@ -8,6 +8,7 @@ import java.util.HashMap;
 import org.onlab.onos.cluster.ControllerNode;
 import org.onlab.onos.cluster.DefaultControllerNode;
 import org.onlab.onos.cluster.NodeId;
+import org.onlab.onos.cluster.RoleInfo;
 import org.onlab.onos.mastership.MastershipTerm;
 import org.onlab.onos.net.ConnectPoint;
 import org.onlab.onos.net.DefaultAnnotations;
@@ -107,7 +108,8 @@ public final class KryoNamespaces {
                     Criterion.Type.class,
                     DefaultTrafficTreatment.class,
                     Instructions.DropInstruction.class,
-                    Instructions.OutputInstruction.class
+                    Instructions.OutputInstruction.class,
+                    RoleInfo.class
                     )
             .register(URI.class, new URISerializer())
             .register(NodeId.class, new NodeIdSerializer())

@@ -3,6 +3,7 @@ package org.onlab.onos.store.serializers;
 import static org.junit.Assert.assertEquals;
 import static org.onlab.onos.net.DeviceId.deviceId;
 import static org.onlab.onos.net.PortNumber.portNumber;
+import static java.util.Arrays.asList;
 
 import java.nio.ByteBuffer;
 
@@ -11,6 +12,7 @@ import org.junit.Before;
 import org.junit.BeforeClass;
 import org.junit.Test;
 import org.onlab.onos.cluster.NodeId;
+import org.onlab.onos.cluster.RoleInfo;
 import org.onlab.onos.mastership.MastershipTerm;
 import org.onlab.onos.net.Annotations;
 import org.onlab.onos.net.ConnectPoint;
@@ -198,6 +200,12 @@ public class KryoSerializerTest {
     }
 
     @Test
+    public void testRoleInfo() {
+        testSerialized(new RoleInfo(new NodeId("master"),
+                            asList(new NodeId("stby1"), new NodeId("stby2"))));
+    }
+
+    @Test
     public void testAnnotations() {
         // Annotations does not have equals defined, manually test equality
         final byte[] a1Bytes = serializer.encode(A1);