docs: private JSONArray retrievePerPartitionTransactionIds() {
          JSONArray retval = new JSONArray();
          try {
              ByteBuffer values = ByteBuffer.wrap(m_zk.getData(VoltZK.perPartitionTxnIds, false, null));
              int numKeys = values.getInt();
              for (int ii = 0; ii < numKeys; ii++) {
                  retval.put(values.getLong());
              }
          } catch (KeeperException.NoNodeException e) {/*doesn't have to exist*/}
          catch (Exception e) {
              VoltDB.crashLocalVoltDB("Failed to retrieve per partition transaction ids for snapshot", false, e);
          }
          return retval;
      }