Added toString to abstract event.
diff --git a/core/api/src/main/java/org/onlab/onos/event/AbstractEvent.java b/core/api/src/main/java/org/onlab/onos/event/AbstractEvent.java
index 93dca8e..f5c9691 100644
--- a/core/api/src/main/java/org/onlab/onos/event/AbstractEvent.java
+++ b/core/api/src/main/java/org/onlab/onos/event/AbstractEvent.java
@@ -1,5 +1,7 @@
 package org.onlab.onos.event;
 
+import static com.google.common.base.MoreObjects.toStringHelper;
+
 /**
  * Base event implementation.
  */
@@ -48,4 +50,10 @@
         return subject;
     }
 
+    @Override
+    public String toString() {
+        return toStringHelper(this).add("time", time).add("type", type())
+                .add("subject", subject()).toString();
+    }
+
 }