Fix json formating for counters

Change-Id: Ibd506936507752a4911aa2cb0bac3ec916d1da71
diff --git a/cli/src/main/java/org/onosproject/cli/net/CountersListCommand.java b/cli/src/main/java/org/onosproject/cli/net/CountersListCommand.java
index 7a22965..3d1bbc4 100644
--- a/cli/src/main/java/org/onosproject/cli/net/CountersListCommand.java
+++ b/cli/src/main/java/org/onosproject/cli/net/CountersListCommand.java
@@ -78,12 +78,12 @@
         // Create a JSON node for partitioned database counter
         ObjectNode jsonPartitionedDatabaseCounters = mapper.createObjectNode();
         jsonPartitionedDatabaseCounters.put("partitionedDatabaseCounters",
-                                            partitionedDbCounters.toString());
+                                            json(partitionedDbCounters));
         jsonCounters.add(jsonPartitionedDatabaseCounters);
         // Create a JSON node for in-memory database counter
         ObjectNode jsonInMemoryDatabseCounters = mapper.createObjectNode();
         jsonInMemoryDatabseCounters.put("inMemoryDatabaseCounters",
-                                        inMemoryDbCounters.toString());
+                                        json(inMemoryDbCounters));
         jsonCounters.add(jsonInMemoryDatabseCounters);
 
         return jsonCounters;