[ONOS-2225] Add codecs with unit test for FlowObjective REST API

* Add codec for FilteringObjective
* Add codec for ForwardingObjective
* Add codec for NextObjective

Change-Id: I715aa7f1969697468692459052fd27cc65ca2363
diff --git a/core/common/src/main/java/org/onosproject/codec/impl/CodecManager.java b/core/common/src/main/java/org/onosproject/codec/impl/CodecManager.java
index 633a356..7c19202 100644
--- a/core/common/src/main/java/org/onosproject/codec/impl/CodecManager.java
+++ b/core/common/src/main/java/org/onosproject/codec/impl/CodecManager.java
@@ -43,6 +43,9 @@
 import org.onosproject.net.flow.TrafficTreatment;
 import org.onosproject.net.flow.criteria.Criterion;
 import org.onosproject.net.flow.instructions.Instruction;
+import org.onosproject.net.flowobjective.FilteringObjective;
+import org.onosproject.net.flowobjective.ForwardingObjective;
+import org.onosproject.net.flowobjective.NextObjective;
 import org.onosproject.net.group.Group;
 import org.onosproject.net.group.GroupBucket;
 import org.onosproject.net.intent.ConnectivityIntent;
@@ -109,6 +112,9 @@
         registerCodec(TableStatisticsEntry.class, new TableStatisticsEntryCodec());
         registerCodec(PortStatistics.class, new PortStatisticsCodec());
         registerCodec(Metric.class, new MetricCodec());
+        registerCodec(FilteringObjective.class, new FilteringObjectiveCodec());
+        registerCodec(ForwardingObjective.class, new ForwardingObjectiveCodec());
+        registerCodec(NextObjective.class, new NextObjectiveCodec());
         log.info("Started");
     }