docs: private Set<Integer> getBalancePartitions(Iv2InitiateTaskMessage msg)
      {
          try {
              JSONObject jsObj = new JSONObject((String) msg.getParameters()[0]);
              BalancePartitionsRequest request = new BalancePartitionsRequest(jsObj);
  
              return Sets.newHashSet(request.partitionPairs.get(0).srcPartition,
                      request.partitionPairs.get(0).destPartition);
          } catch (JSONException e) {
              hostLog.warn("Unable to determine partitions for @BalancePartitions", e);
              return null;
          }
      }