Added @Beta annotation to the flow objective API.

Change-Id: I4dd91921db1ff533b0ea1e3244dcdbf08b64a499
diff --git a/core/api/src/main/java/org/onosproject/net/flowobjective/ObjectiveEvent.java b/core/api/src/main/java/org/onosproject/net/flowobjective/ObjectiveEvent.java
index 9f095cf..c6937e3 100644
--- a/core/api/src/main/java/org/onosproject/net/flowobjective/ObjectiveEvent.java
+++ b/core/api/src/main/java/org/onosproject/net/flowobjective/ObjectiveEvent.java
@@ -15,11 +15,13 @@
  */
 package org.onosproject.net.flowobjective;
 
+import com.google.common.annotations.Beta;
 import org.onosproject.event.AbstractEvent;
 
 /**
  * Describes a objective event.
  */
+@Beta
 public class ObjectiveEvent extends AbstractEvent<ObjectiveEvent.Type, Integer> {
 
     /**