Refeactor codec helper classes

Change-Id: Ic980293f5df97ed74a73fc54e3dcb197658264f5
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 e903dfa..6f680c8 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
@@ -56,7 +56,7 @@
     public ObjectNode encode(Instruction instruction, CodecContext context) {
         checkNotNull(instruction, "Instruction cannot be null");
 
-        return new EncodeInstructionCodec(instruction, context).encode();
+        return new EncodeInstructionCodecHelper(instruction, context).encode();
     }
 
     @Override
@@ -65,6 +65,6 @@
             return null;
         }
 
-        return new DecodeInstructionCodec(json).decode();
+        return new DecodeInstructionCodecHelper(json).decode();
     }
 }