@Override
        public List<String> convert(String text, String field, String... langs) throws IOException {
            if (text == null || text.isEmpty()) {
                return Collections.emptyList();
            }

            List<String> readings = new ArrayList<>();

            if (langs == null || langs.length == 0) {
                readings.add(text.toUpperCase());
            } else {

public interface Normalizer {
    /**
     * Normalizes the given text.
     * @param text The text to normalize
     * @param field The field name
     * @param langs The language
     * @return The normalized text
     */
    String normalize(String text, String field, String... langs);

    List<Normalizer> normalizers = new ArrayList<>();

    @Override
    public String normalize(final String text, final String field, final String... langs) {
        String tmp = text;
        for (final Normalizer normalizer : normalizers) {
            tmp = normalizer.normalize(tmp, field, langs);
        }
        return tmp;
    }

    /**
     * Adds a normalizer to the chain.
     * @param normalizer The normalizer to add.

    public String normalize(final String text, final String field, final String... langs) {
        final Normalizer normalizer;
        if (langs == null || langs.length == 0) {
            normalizer = new LangAnalyzerNormalizer(null);
        } else {
            final NormalizerChain chain = new NormalizerChain();
            for (final String lang : langs) {
                chain.add(new LangAnalyzerNormalizer(lang));
            }

     * @param searchWord Search word
     * @param field Field
     * @param langs Languages
     * @param analyzer Analyzer
     * @return True if the search word is excluded
     */
    protected boolean isExcludeSearchword(final String searchWord, final String field, final String[] langs,
            final SuggestAnalyzer analyzer) {
        if (langs == null || langs.length == 0) {

        final ReadingConverter converter;
        if (langs == null || langs.length == 0) {
            converter = new LangAnalyzerConverter(null);
        } else {
            final ReadingConverterChain chain = new ReadingConverterChain();
            for (final String lang : langs) {
                chain.addConverter(new LangAnalyzerConverter(lang));

     * @param field the field to be used for conversion.
     * @param langs the languages to be used for conversion.
     * @return a list of readings for the given text.
     * @throws IOException if an I/O error occurs during conversion.
     */
    List<String> convert(String text, final String field, String... langs) throws IOException;

        // Test convert with null languages
        String text = "test text";
        String field = "content";
        String[] langs = null;

        List<String> results = converter.convert(text, field, langs);

        assertNotNull(results);
        // Results may vary based on analyzer configuration
    }

    @Test

     * @param normalizer the normalizer to use for normalizing the search words
     * @param analyzer the analyzer to use for analyzing the search words
     * @param langs the array of languages associated with the search words
     * @return a SuggestItem created from the given search words and associated data
     */

     */
    public FullWidthToHalfWidthAlphabetNormalizer() {
        // nothing
    }

    @Override
    public String normalize(final String text, final String field, final String... langs) {
        final char[] chars = new char[text.length()];
        for (int i = 0; i < chars.length; i++) {
            final char c = text.charAt(i);
            if (c >= 'ａ' && c <= 'ｚ') {