}
        encodingMap.put(toLowerCase(source), target);
    }

    /**
     * Converts the given encoding string to lowercase.
     * @param enc The encoding string.
     * @return The lowercase encoding string.
     */
    protected String toLowerCase(final String enc) {
        return enc.toLowerCase(Locale.ROOT);
    }

     */
    private CharUtil() {
    }

    /**
     * Checks if the given character is a valid URL character.
     *
     * Valid URL characters include:
     * - Lowercase letters (a-z)
     * - Uppercase letters (A-Z)
     * - Digits (0-9)
     * - Special characters: . - * _ : / + % = & ? # [ ] @ ~ ! $ ' ( ) , ;
     *
     * @param c the character to check