class ConfigImportSubscriber

class ConfigImportSubscriber extends ConfigImportValidateEventSubscriberBase {
    
    /**
     * The config manager.
     *
     * @var \Drupal\Core\Config\ConfigManagerInterface
     */
    protected $configManager;
    
    /**
     * The entity type manager.
     *
     * @var \Drupal\Core\Entity\EntityTypeManagerInterface
     */
    protected $entityTypeManager;
    
    /**
     * Constructs the event subscriber.
     *
     * @param \Drupal\Core\Config\ConfigManagerInterface $config_manager
     *   The config manager
     * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
     *   The entity type manager.
     */
    public function __construct(ConfigManagerInterface $config_manager, EntityTypeManagerInterface $entity_type_manager) {
        $this->configManager = $config_manager;
        $this->entityTypeManager = $entity_type_manager;
    }
    
    /**
     * {@inheritdoc}
     */
    public function onConfigImporterValidate(ConfigImporterEvent $event) {
        foreach ([
            'update',
            'delete',
        ] as $op) {
            $unprocessed_configurations = $event->getConfigImporter()
                ->getUnprocessedConfiguration($op);
            foreach ($unprocessed_configurations as $unprocessed_configuration) {
                if ($workflow = $this->getWorkflow($unprocessed_configuration)) {
                    if ($op === 'update') {
                        $original_workflow_config = $event->getConfigImporter()
                            ->getStorageComparer()
                            ->getSourceStorage()
                            ->read($unprocessed_configuration);
                        $workflow_config = $event->getConfigImporter()
                            ->getStorageComparer()
                            ->getTargetStorage()
                            ->read($unprocessed_configuration);
                        $diff = array_diff_key($workflow_config['type_settings']['states'], $original_workflow_config['type_settings']['states']);
                        foreach (array_keys($diff) as $state_id) {
                            $state = $workflow->getTypePlugin()
                                ->getState($state_id);
                            if ($workflow->getTypePlugin()
                                ->workflowStateHasData($workflow, $state)) {
                                $event->getConfigImporter()
                                    ->logError($this->t('The moderation state @state_label is being used, but is not in the source storage.', [
                                    '@state_label' => $state->label(),
                                ]));
                            }
                        }
                    }
                    if ($op === 'delete') {
                        if ($workflow->getTypePlugin()
                            ->workflowHasData($workflow)) {
                            $event->getConfigImporter()
                                ->logError($this->t('The workflow @workflow_label is being used, and cannot be deleted.', [
                                '@workflow_label' => $workflow->label(),
                            ]));
                        }
                    }
                }
            }
        }
    }
    
    /**
     * Get the workflow entity object from the configuration name.
     *
     * @param string $config_name
     *   The configuration object name.
     *
     * @return \Drupal\workflows\WorkflowInterface|null
     *   A workflow entity object. NULL if no matching entity is found.
     */
    protected function getWorkflow($config_name) {
        $entity_type_id = $this->configManager
            ->getEntityTypeIdByName($config_name);
        if ($entity_type_id !== 'workflow') {
            return;
        }
        
        /** @var \Drupal\Core\Config\Entity\ConfigEntityTypeInterface $entity_type */
        $entity_type = $this->entityTypeManager
            ->getDefinition($entity_type_id);
        $entity_id = ConfigEntityStorage::getIDFromConfigName($config_name, $entity_type->getConfigPrefix());
        return $this->entityTypeManager
            ->getStorage($entity_type_id)
            ->load($entity_id);
    }

}