Finished implementation of GossipIntentStore based on new API and semantics.

Change-Id: I1a71d075e5d34ab7b9f7c2533d389235d6da1d9a
diff --git a/core/store/dist/src/main/java/org/onosproject/store/impl/ClockService.java b/core/store/dist/src/main/java/org/onosproject/store/impl/ClockService.java
index 4fbfc22..3ed89f8 100644
--- a/core/store/dist/src/main/java/org/onosproject/store/impl/ClockService.java
+++ b/core/store/dist/src/main/java/org/onosproject/store/impl/ClockService.java
@@ -18,15 +18,18 @@
 import org.onosproject.store.Timestamp;
 
 /**
- * Clock service that can generate timestamps per object.
+ * Clock service that can generate timestamps based off of two input objects.
+ * Implementations are free to only take one or none of the objects into account
+ * when generating timestamps.
  */
-public interface ClockService<T> {
+public interface ClockService<T, U> {
 
     /**
-     * Gets a new timestamp for the given object.
+     * Gets a new timestamp for the given objects.
      *
-     * @param object Object to get a timestamp for
+     * @param object1 First object to use when generating timestamps
+     * @param object2 Second object to use when generating timestamps
      * @return the new timestamp
      */
-    public Timestamp getTimestamp(T object);
+    public Timestamp getTimestamp(T object1, U object2);
 }