ONOS-2581 Add codec for tunnel id

Change-Id: I6ff456b0419b427945cc53fb74fd0a91cdfa758e
diff --git a/core/common/src/main/java/org/onosproject/codec/impl/CriterionCodec.java b/core/common/src/main/java/org/onosproject/codec/impl/CriterionCodec.java
index 8a6a729..76f621f 100644
--- a/core/common/src/main/java/org/onosproject/codec/impl/CriterionCodec.java
+++ b/core/common/src/main/java/org/onosproject/codec/impl/CriterionCodec.java
@@ -60,6 +60,7 @@
     protected static final String SPACING_MULIPLIER = "spacingMultiplier";
     protected static final String SLOT_GRANULARITY = "slotGranularity";
     protected static final String OCH_SIGNAL_ID = "ochSignalId";
+    protected static final String TUNNEL_ID = "tunnelId";
 
     @Override
     public ObjectNode encode(Criterion criterion, CodecContext context) {