/**
   * The input files for each ngram level is read, splitted according to the frequency of the words
   * starting letter in the files and the split files are individually sorted and consolidated.
   */
  @Override
  public void collectionProcessComplete() throws AnalysisEngineProcessException {
    super.collectionProcessComplete();

    try {
      converter.createIndex();
    } catch (IOException e) {
      throw new AnalysisEngineProcessException(e);
    }
  }