public static String escape(final String raw) {
        if (raw == null) {
            return "";
        }
        return ESCAPE_CHAR_FINDER.matcher(raw).replaceAll("" + ESCAPE_CHAR + ESCAPE_CHAR + "$1");
    }
Escapes all characters with a backslash (\) which could have a special meaning in context of expressions.
Those are: ()=:[]; and the backslash \ itself

@param raw string to escape
@return escaped string
main/src/main/java/cgeo/geocaching/utils/config/LegacyFilterConfigParser.java