Setting navigation group as collapsed by default

class RelationFilamentResource extends Resource
{
    ...

    public static function getNavigationLabel(): string
    {
        return 'Relations';
    }

    public static function getNavigationGroup(): ?string
    {
        return 'Reservations';  // <--- same navigation group that should be collapsed by default!
    }

    ...

class PaymentFilamentResource extends Resource
{
    ...

    public static function getNavigationLabel(): string
    {
        return 'Payments';
    }

    public static function getNavigationGroup(): ?string
    {
        return 'Reservations';  // <--- same navigation group that should be collapsed by default!
    }

    ...