The method could be simplified like so:

    static int powerOfPropertyOr(String name, int defaultPower) {
        final String property = GetPropertyAction.privilegedGetProperty(PROPERTY_PATH + name, Integer.toString(defaultPower));
        try {
            return 1 << Math.clamp(Integer.parseInt(property), 0, Integer.SIZE - 2);
        } catch (NumberFormatException _) {
            // ignore
        }
        return defaultPower;
    }