isStrict example

        $criteria = new Criteria();
        $criteria->addAssociation('mediaFolder.configuration.mediaThumbnailSizes');
        $criteria->addFilter(new EqualsAnyFilter('media.id', $msg->getMediaIds()));

        /** @var MediaCollection $entities */
        $entities = $this->mediaRepository->search($criteria, $context)->getEntities();

        if ($msg instanceof UpdateThumbnailsMessage) {
            foreach ($entities as $media) {
                $this->thumbnailService->updateThumbnails($media, $context, $msg->isStrict());
            }
        } else {
            $this->thumbnailService->generate($entities, $context);
        }
    }
}