private Set<byte[]> getOrCreateFamilies() {
    if (this.families == null) {
      this.families = new TreeSet<>(Bytes.BYTES_COMPARATOR);
    }
    return this.families;
  }
Create a new WALEdit from a existing {@link WALEdit}.
hbase-server/src/main/java/org/apache/hadoop/hbase/wal/WALEdit.java