static Set<byte[]> collectFamilies(List<ExtendedCell> cells) {
    if (CollectionUtils.isEmpty(cells)) {
      return Collections.emptySet();
    } else {
      Set<byte[]> set = new TreeSet<>(Bytes.BYTES_COMPARATOR);
      for (Cell cell : cells) {
        if (!WALEdit.isMetaEditFamily(cell)) {
          set.add(CellUtil.cloneFamily(cell));
        }
      }
      return set;
    }
  }
@param inMemstore If true, then this is a data edit, one that came from client. If false, it is
                  a meta edit made by the hbase system itself and is for the WAL only.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/FSWALEntry.java