ONOS-6468 Fix for race condition between compilation and installation complete state.

- Fix for a bug where intent compilation complete state,
  can overwrites intent installation complete state,
  if intent installation completes before compilation complete state is written to the store.
  - Introduced internalState version on IntentData,
    which is effectively mutation count, in order to avoid
    batch write of compilation result overwriting installation result

Change-Id: I5d77dfbe496e690ebdf2b4f9643d2b64c4233182
diff --git a/core/api/src/main/java/org/onosproject/store/service/WallClockTimestamp.java b/core/api/src/main/java/org/onosproject/store/service/WallClockTimestamp.java
index eb634da..e96649c 100644
--- a/core/api/src/main/java/org/onosproject/store/service/WallClockTimestamp.java
+++ b/core/api/src/main/java/org/onosproject/store/service/WallClockTimestamp.java
@@ -19,9 +19,9 @@
 
 import java.util.Objects;
 
+import org.joda.time.DateTime;
 import org.onosproject.store.Timestamp;
 
-import com.google.common.base.MoreObjects;
 import com.google.common.collect.ComparisonChain;
 
 /**
@@ -69,9 +69,7 @@
 
     @Override
     public String toString() {
-        return MoreObjects.toStringHelper(getClass())
-                    .add("unixTimestamp", unixTimestamp)
-                    .toString();
+        return new DateTime(unixTimestamp).toString();
     }
 
     /**