private long getTotalStoreSize(List<HStoreFile> potentialMatchFiles) {
    return potentialMatchFiles.stream().mapToLong(sf -> sf.getReader().length()).sum();
  }
Find the total size of a list of store files.
@param potentialMatchFiles StoreFile list.
@return Sum of StoreFile.getReader().length();
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/compactions/ExploringCompactionPolicy.java