ONOS-4380 Refactor AlarmId and Alarm construction and update

Change-Id: I0117afda723ba27aadb1db306f7ce15b666f102d
diff --git a/apps/faultmanagement/fmmgr/src/main/java/org/onosproject/faultmanagement/api/AlarmStore.java b/apps/faultmanagement/fmmgr/src/main/java/org/onosproject/faultmanagement/api/AlarmStore.java
index 716449b..0b857f3 100644
--- a/apps/faultmanagement/fmmgr/src/main/java/org/onosproject/faultmanagement/api/AlarmStore.java
+++ b/apps/faultmanagement/fmmgr/src/main/java/org/onosproject/faultmanagement/api/AlarmStore.java
@@ -53,11 +53,12 @@
     Collection<Alarm> getAlarms(DeviceId deviceId);
 
     /**
-     * Stores an alarm.
+     * Stores or updates an alarm.
      *
      * @param alarm alarm
      */
-    void setAlarm(Alarm alarm);
+
+    void createOrUpdateAlarm(Alarm alarm);
 
     /**
      * Removes an alarm.