public Map<TConsensusGroupId, Pair<RegionGroupStatistics, RegionGroupStatistics>>
      getDifferentRegionGroupStatisticsMap() {
    return differentRegionGroupStatisticsMap;
  }
RegionGroupStatisticsChangeEvent represents the change of RegionGroup statistics.
iotdb-core/confignode/src/main/java/org/apache/iotdb/confignode/manager/load/subscriber/RegionGroupStatisticsChangeEvent.java