private function buildSelectorForExcerpt($locale, &$additionalFields)
    {
        $excerptStructure = $this->structureManager->getStructure('excerpt');
        $extension = $this->extensionManager->getExtension('', 'excerpt');

        foreach ($excerptStructure->getProperties(true) as $property) {
            $additionalFields[$locale][] = [
                'extension' => $extension,
                'target' => 'excerpt',
                'property' => $property->getName(),
                'name' => $property->getName(),
            ];
        }
    }