Fix missing references and missing description in Javadoc

Change-Id: Ia49ed4e2b054cf54f54c3ec2f77cdd1ecb1ffec1
diff --git a/src/main/java/net/floodlightcontroller/util/EventHistory.java b/src/main/java/net/floodlightcontroller/util/EventHistory.java
index 40c9a36..d6e08d5 100644
--- a/src/main/java/net/floodlightcontroller/util/EventHistory.java
+++ b/src/main/java/net/floodlightcontroller/util/EventHistory.java
@@ -153,7 +153,7 @@
      * for the next event of the same type
      *
      * @param t
-     * @param op
+     * @param action
      * @return
      */