return "";
        }
        final StringBuilder sb = new StringBuilder(filter.length() * 2);
        for (int i = 0; i < filter.length(); i++) {
            final char curChar = filter.charAt(i);
            switch (curChar) {
            case '\\':
                sb.append("\\5c");
                break;
            case '*':
                sb.append("\\2a");
                break;