public List<RegionMaintainTask> getRegionMaintainEntryList() {
    synchronized (regionMaintainTaskList) {
      return new ArrayList<>(regionMaintainTaskList);
    }
  }
Get a deep copy of RegionCleanList for RegionCleaner to maintain cluster RegionReplicas.

@return A deep copy of RegionCleanList
iotdb-core/confignode/src/main/java/org/apache/iotdb/confignode/persistence/partition/PartitionInfo.java