private Class classFor(final String name) {
        if (name == null) throw new NullPointerException("missing required 'type' filter config parameter");
        Class cl = null;
        try {
            return Class.forName(name);
        } catch (ClassNotFoundException e) {
        }
        try {
            return Class.forName(DEFAULT_PACKAGE + name + "Filter");
        } catch (ClassNotFoundException e) {
        }
        if (cl == null) {
            throw new Error("failed to load class for Filter type '" + name + "'");
        }
        return cl;
    }