/** Tokenizer factory. */
    protected TokenizerFactory tokenizerFactory = null;

    /**
     * Default constructor.
     */
    public KatakanaConverter() {
        // nothing
    }

    /**
     * Constructor with a tokenizer factory.
     * @param tokenizerFactory The tokenizer factory to use.
     */
    public KatakanaConverter(final TokenizerFactory tokenizerFactory) {

        extra.put("disable_graph", DisableGraphFilterFactory::new);
        return extra;
    }

    @Override
    public Map<String, AnalysisProvider<TokenizerFactory>> getTokenizers() {
        final Map<String, AnalysisProvider<TokenizerFactory>> extra = new HashMap<>();
        extra.put("reloadable_kuromoji_tokenizer", KuromojiTokenizerFactory::new);
        extra.put("reloadable_kuromoji", KuromojiTokenizerFactory::new);