code: private void mergeConsumerDrIdTrackerToZK(JSONObject jsonObj) throws JSONException {
          //DR ids/unique ids for remote partitions indexed by remote datacenter id,
          //each DC has a full partition set
          JSONObject dcIdMap;
          if (jsonObj.has("drMixedClusterSizeConsumerState")) {
              dcIdMap = jsonObj.getJSONObject("drMixedClusterSizeConsumerState");
          } else {
              dcIdMap = new JSONObject();
              jsonObj.put("drMixedClusterSizeConsumerState", dcIdMap);
          }
  
          for (Map.Entry<Integer, JSONObject> dcEntry : m_drMixedClusterSizeConsumerState.entrySet()) {
              //Last seen ids for a specific data center
              final String consumerPartitionString = dcEntry.getKey().toString();
              if (!dcIdMap.has(consumerPartitionString)) {
                  dcIdMap.put(consumerPartitionString, dcEntry.getValue());
              }
          }
      }
docs: /*
  When recording snapshot completion we also record DR remote DC unique ids
  as JSON. Need to merge our unique ids with existing numbers
  since multiple replicas will submit the unique ids