Global widget filter is null

    protected function getHeaderActions(): array
    {
        return [
            FilterAction::make()
                ->form([
                    DatePicker::make('startDate')
                        ->label('Startdatum')
                        ->default(now()->startOfYear()),
                    DatePicker::make('endDate')
                        ->label('Einddatum')
                        ->default(now()->endOfYear()),
                ])
        ];
    }