ONOS-4380 Refactor AlarmId and Alarm construction and update

Change-Id: I0117afda723ba27aadb1db306f7ce15b666f102d
diff --git a/incubator/api/src/main/java/org/onosproject/incubator/net/faultmanagement/alarm/AlarmEvent.java b/incubator/api/src/main/java/org/onosproject/incubator/net/faultmanagement/alarm/AlarmEvent.java
index 9481b01..167d7f6 100644
--- a/incubator/api/src/main/java/org/onosproject/incubator/net/faultmanagement/alarm/AlarmEvent.java
+++ b/incubator/api/src/main/java/org/onosproject/incubator/net/faultmanagement/alarm/AlarmEvent.java
@@ -33,6 +33,10 @@
          */
         CREATED,
         /**
+         * Individual alarm updated.
+         */
+        UPDATED,
+        /**
          * Alarm set updated for a given device.
          */
         REMOVED,