Fix for [ONOS-5825]

Changes:
- Adds exception management in the mgr;
- Improve logging of the clean up;

Change-Id: I3ca94761e5b4550b7f8df34e9de4a481bc546be3
diff --git a/core/store/dist/src/main/java/org/onosproject/store/intent/impl/GossipIntentStore.java b/core/store/dist/src/main/java/org/onosproject/store/intent/impl/GossipIntentStore.java
index 5d12e04..9da2e39 100644
--- a/core/store/dist/src/main/java/org/onosproject/store/intent/impl/GossipIntentStore.java
+++ b/core/store/dist/src/main/java/org/onosproject/store/intent/impl/GossipIntentStore.java
@@ -292,11 +292,9 @@
                 currentMap.put(newData.key(), new IntentData(newData));
             }
         }
-        /*
-         * Remove the intent data from the pending map if the newData is more
-         * recent or equal to the existing entry. No matter if it is an acceptable
-         * update or not.
-         */
+        // Remove the intent data from the pending map if the newData is more
+        // recent or equal to the existing entry. No matter if it is an acceptable
+        // update or not
         pendingMap.compute(newData.key(), (key, existingValue) -> {
             if (existingValue == null || !existingValue.version().isNewerThan(newData.version())) {
                 return null;