code: public static String taskListToString(List<RebalanceTaskInfo> infos) {
          StringBuffer sb = new StringBuffer();
          for (RebalanceTaskInfo info : infos) {
              sb.append("\t").append(info.getDonorId()).append(" -> ").append(info.getStealerId()).append(" : [");
              for (String storeName : info.getPartitionStores()) {
                  sb.append("{").append(storeName).append(" : ").append(info.getPartitionIds(storeName)).append("}");
              }
              sb.append("]").append(Utils.NEWLINE);
          }
          return sb.toString();
      }
docs: Pretty prints a task list of rebalancing tasks.
  
  @param infos list of rebalancing tasks (RebalancePartitionsInfo)
  @return pretty-printed string