code: public Automaton getAutomatonById(String id) throws IOException {
      if (idToVersion.containsKey(id)) {
        List<BytesRef> bytesArray = new ArrayList<>();
        Set<String> data = get(id);
        if (data != null) {
          Term term;
          for (String item : data) {
            term = new Term("dummy", item);
            bytesArray.add(term.bytes());
          }
          Collections.sort(bytesArray);
          return Automata.makeStringUnion(bytesArray);
        }
      }
      return null;
    }
docs: Gets the automaton by id.
  
  @param id the id
  @return the automaton by id
  @throws IOException Signals that an I/O exception has occurred.