protected function indexDropdownFilters(): array
    {
        $aFilters = [];
        if (classUses(static::getModel(), Localised::class)) {

            /** @var Locale $oLocale */
            $oLocale = Factory::service('Locale');

            $aOptions   = [];
            $aOptions[] = Factory::factory('IndexFilterOption', 'nails/module-admin')
                ->setLabel('All Locales');

            foreach ($oLocale->getSupportedLocales() as $oSupportedLocale) {
                $aOptions[] = Factory::factory('IndexFilterOption', 'nails/module-admin')
                    ->setLabel($oSupportedLocale->getDisplayLanguage())
                    ->setValue($oSupportedLocale->getLanguage() . '_' . $oSupportedLocale->getRegion());
            }

            $aFilters[] = Factory::factory('IndexFilter', 'nails/module-admin')
                ->setLabel('Locale')
                ->setColumn('CONCAT(`language`, \'_\', `region`)')
                ->addOptions($aOptions);
        }

        return $aFilters;
    }