Define ID representation for Intent, IFlow and MatchAction

- Defines BatchOperationTargetId abstract class.
- The above class is the base class of IntentId, FlowId, and MatchActionId.
 -- Intent objects use IntentId class for its ID.
 -- IFlow objects use FlowId class for its ID.
 -- MatchAction objects use MatchActionId class for its ID.
- BatchOperation classes requires the BatchOperationTargetId as the target object's ID.
- This work is a part of ONOS-1758.

Change-Id: I71bb4e6acd3836d1ced3beb6fb331bca451abdc3
diff --git a/src/main/java/net/onrc/onos/core/matchaction/MatchAction.java b/src/main/java/net/onrc/onos/core/matchaction/MatchAction.java
index 2f21baf..cf4bf0f 100644
--- a/src/main/java/net/onrc/onos/core/matchaction/MatchAction.java
+++ b/src/main/java/net/onrc/onos/core/matchaction/MatchAction.java
@@ -18,7 +18,7 @@
  * A filter and actions for traffic.
  */
 public class MatchAction implements IBatchOperationTarget {
-    protected String id;
+    protected final MatchActionId id;
     protected SwitchPort port;
     protected List<IMatch> matches;
     protected List<IAction> actions;
@@ -33,7 +33,7 @@
      */
     public MatchAction(String id, SwitchPort port, List<IMatch> matches,
             List<IAction> actions) {
-        this.id = id;
+        this.id = new MatchActionId(id);
         this.port = port;
         this.matches = matches;
         this.actions = actions;
@@ -64,7 +64,7 @@
     }
 
     @Override
-    public String getId() {
+    public MatchActionId getId() {
         return id;
     }