class ContentUninstallValidator

class ContentUninstallValidator implements ModuleUninstallValidatorInterface {
    use StringTranslationTrait;
    
    /**
     * The entity type manager service.
     *
     * @var \Drupal\Core\Entity\EntityTypeManagerInterface
     */
    protected $entityTypeManager;
    
    /**
     * Constructs a new ContentUninstallValidator.
     *
     * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
     *   The entity type manager service.
     * @param \Drupal\Core\StringTranslation\TranslationInterface $string_translation
     *   The string translation service.
     */
    public function __construct(EntityTypeManagerInterface $entity_type_manager, TranslationInterface $string_translation) {
        $this->entityTypeManager = $entity_type_manager;
        $this->stringTranslation = $string_translation;
    }
    
    /**
     * {@inheritdoc}
     */
    public function validate($module) {
        $entity_types = $this->entityTypeManager
            ->getDefinitions();
        $reasons = [];
        foreach ($entity_types as $entity_type) {
            if ($module == $entity_type->getProvider() && $entity_type instanceof ContentEntityTypeInterface && $this->entityTypeManager
                ->getStorage($entity_type->id())
                ->hasData()) {
                $reasons[] = $this->t('There is content for the entity type: @entity_type. <a href=":url">Remove @entity_type_plural</a>.', [
                    '@entity_type' => $entity_type->getLabel(),
                    '@entity_type_plural' => $entity_type->getPluralLabel(),
                    ':url' => Url::fromRoute('system.prepare_modules_entity_uninstall', [
                        'entity_type_id' => $entity_type->id(),
                    ])
                        ->toString(),
                ]);
            }
        }
        return $reasons;
    }

}