code: int transfer(Long maxTaskId, long oldPartitionId) throws Exception {
          long partitionId = getPartitionId();
  
          TransactionController tranController = new TransactionController();
          int count = 0;
          try {
              tranController.preInvoke();
  
              count = taskStore.transfer(maxTaskId, oldPartitionId, partitionId);
  
              Config config = configRef.get();
              if (config.enableTaskExecution && count > 0 && config.pollInterval < 0) {
                  // Schedule a poll to find the transferred tasks
                  Synchronization autoPoll = new PollingTask(config);
                  UOWCurrent uowCurrent = (UOWCurrent) tranController.tranMgr;
                  tranController.tranMgr.registerSynchronization(uowCurrent.getUOWCoord(), autoPoll, EmbeddableWebSphereTransactionManager.SYNC_TIER_OUTER);
              }
          } catch (Throwable x) {
              tranController.setFailure(x);
          } finally {
              Exception x = tranController.postInvoke(Exception.class);
              if (x != null)
                  throw x;
          }
  
          return count;
      }
docs: Transfers tasks that have not yet ended to this persistent executor instance.
  
  This method is for the mbean only.
  
  @param maxTaskId task id including and up to which to transfer non-ended tasks from the old partition to this partition.
  If null, all non-ended tasks are transferred from the old partition to this partition.
  @param oldPartitionId partition id to which tasks are currently assigned.
  @return count of transferred tasks.