public static OptionalLong getMaxMemStoreTSInList(Collection<HStoreFile> sfs) {
    return sfs.stream().filter(sf -> !sf.isBulkLoadResult()).mapToLong(HStoreFile::getMaxMemStoreTS)
      .max();
  }
Return the largest memstoreTS found across all storefiles in the given list. Store files that
were created by a mapreduce bulk load are ignored, as they do not correspond to any specific
put operation, and thus do not have a memstoreTS associated with them.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/StoreUtils.java