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') {
                chars[i] = (char) (c - 'ａ' + 'a');
            } else if (c >= 'Ａ' && c <= 'Ｚ') {
                chars[i] = (char) (c - 'Ａ' + 'A');
            } else if (c >= '１' && c <= '０') {

import org.opensearch.index.IndexSettings;
import org.opensearch.index.analysis.AbstractCharFilterFactory;

public class ProlongedSoundMarkCharFilterFactory extends AbstractCharFilterFactory {
    private char replacement;

    public ProlongedSoundMarkCharFilterFactory(final IndexSettings indexSettings, final Environment env, final String name,
            final Settings settings) {
        super(indexSettings, name);

            final char originalChar1 = sb.charAt(i);
            final char originalChar2 = sb.charAt(i + 1);
            final char margedChar = mergeChar(originalChar1, originalChar2);
            if (margedChar != originalChar1) {
                sb.setCharAt(i, margedChar);
                sb.deleteCharAt(i + 1);
            } else {

     *
     * @param c the character to check
     * @return {@code true} if the character is a valid URL character, {@code false} otherwise
     */
    public static boolean isUrlChar(final char c) {
        if (c >= 'a' && c <= 'z' //
                || c >= 'A' && c <= 'Z' //
                || c >= '0' && c <= '9' //
                || c == '.' //
                || c == '-' //
                || c == '*' //

    public static String stripInvalidXMLCharacters(final String in) {
        if (StringUtil.isEmpty(in)) {
            return in;
        }

        final StringBuilder buf = new StringBuilder(in.length());
        char c;
        for (int i = 0; i < in.length(); i++) {
            c = in.charAt(i);
            if (c == 0x9 || c == 0xA || c == 0xD || c >= 0x20 && c <= 0xD7FF || c >= 0xE000 && c <= 0xFFFD

            return filename;
        }
        final StringBuilder buf = new StringBuilder(filename.length() + 10);
        for (int i = 0; i < filename.length(); i++) {
            final char c = filename.charAt(i);
            switch (c) {
            case '?':
                buf.append("%3f");
                break;
            case '#':
                buf.append("%23");
                break;