Unit tests for AtomicValueEvent and SetEvent

Change-Id: I44562365f3076b7cc1afaf5cef9e5be584b432e9
diff --git a/core/api/src/main/java/org/onosproject/store/service/SetEvent.java b/core/api/src/main/java/org/onosproject/store/service/SetEvent.java
index e294bae..a869e72 100644
--- a/core/api/src/main/java/org/onosproject/store/service/SetEvent.java
+++ b/core/api/src/main/java/org/onosproject/store/service/SetEvent.java
@@ -24,7 +24,7 @@
  *
  * @param <E> set element type
  */
-public class SetEvent<E> {
+public final class SetEvent<E> {
 
     /**
      * SetEvent type.
@@ -91,7 +91,7 @@
             return false;
         }
 
-        SetEvent<E> that = (SetEvent) o;
+        SetEvent that = (SetEvent) o;
         return Objects.equals(this.name, that.name) &&
                 Objects.equals(this.type, that.type) &&
                 Objects.equals(this.entry, that.entry);