Fix some JSON related deprecation and javadoc warnings

Change-Id: If39c0bbe578794c8308b24d9290e269bd14b9219
diff --git a/apps/metrics/topology/src/main/java/org/onosproject/metrics/topology/cli/TopologyEventsMetricsCommand.java b/apps/metrics/topology/src/main/java/org/onosproject/metrics/topology/cli/TopologyEventsMetricsCommand.java
index 4205dfa..274a14d 100644
--- a/apps/metrics/topology/src/main/java/org/onosproject/metrics/topology/cli/TopologyEventsMetricsCommand.java
+++ b/apps/metrics/topology/src/main/java/org/onosproject/metrics/topology/cli/TopologyEventsMetricsCommand.java
@@ -85,8 +85,8 @@
         Gauge<Long> gauge = eventMetric.lastEventTimestampGauge();
         Meter meter = eventMetric.eventRateMeter();
 
-        objectNode.put(gaugeName, json(mapper, gauge));
-        objectNode.put(meterName, json(mapper, meter));
+        objectNode.set(gaugeName, json(mapper, gauge));
+        objectNode.set(meterName, json(mapper, meter));
         return objectNode;
     }