docs: public List<String> mergeAndGetDictionary()
    {
      final Set<String> mergedDictionary = new HashSet<>();
      mergedDictionary.addAll(keySerde.getDictionary());
  
      for (File dictFile : dictionaryFiles) {
        try (
            final MappingIterator<String> dictIterator = spillMapper.readValues(
                spillMapper.getFactory().createParser(new LZ4BlockInputStream(new FileInputStream(dictFile))),
                spillMapper.getTypeFactory().constructType(String.class)
            )
        ) {
          while (dictIterator.hasNext()) {
            mergedDictionary.add(dictIterator.next());
          }
        }
        catch (IOException e) {
          throw new RuntimeException(e);
        }
      }
  
      return new ArrayList<>(mergedDictionary);
    }