[ONOS-7583]Adding PI flow rules via REST API and unit tests

Change-Id: I15537097e7b6f8138f8ae43676d5dd22d8b9093a
diff --git a/core/common/src/main/java/org/onosproject/codec/impl/InstructionCodec.java b/core/common/src/main/java/org/onosproject/codec/impl/InstructionCodec.java
index 6e36ec0..75192a0 100644
--- a/core/common/src/main/java/org/onosproject/codec/impl/InstructionCodec.java
+++ b/core/common/src/main/java/org/onosproject/codec/impl/InstructionCodec.java
@@ -65,6 +65,11 @@
     static final String STAT_PACKET_COUNT = "packetCount";
     static final String STAT_DURATION = "duration";
 
+    static final String PI_ACTION_ID = "actionId";
+    static final String PI_ACTION_GROUP_ID = "groupId";
+    static final String PI_ACTION_GROUP_MEMBER_ID = "memberId";
+    static final String PI_ACTION_PARAMS = "actionParams";
+
     static final String MISSING_MEMBER_MESSAGE =
             " member is required in Instruction";
     static final String ERROR_MESSAGE =