Remove unnecessary Object declaration in type parameter

Change-Id: I466a2d43e9f9d3effd3860761a97855110b71781
diff --git a/core/api/src/main/java/org/onosproject/event/Event.java b/core/api/src/main/java/org/onosproject/event/Event.java
index f04ae61..4d588df 100644
--- a/core/api/src/main/java/org/onosproject/event/Event.java
+++ b/core/api/src/main/java/org/onosproject/event/Event.java
@@ -18,7 +18,7 @@
 /**
  * Abstraction of an of a time-stamped event pertaining to an arbitrary subject.
  */
-public interface Event<T extends Enum, S extends Object> {
+public interface Event<T extends Enum, S> {
 
     /**
      * Returns the timestamp of when the event occurred, given in milliseconds