ConfigEntityStorage::doSave

protected ConfigEntityStorage::doSave($id, EntityInterface $entity)

protected function doSave($id, EntityInterface $entity) {
  $is_new = $entity->isNew();
  $prefix = $this->getPrefix();
  $config_name = $prefix . $entity->id();
  if ($id !== $entity->id()) {
    // Renaming a config object needs to cater for:
    // - Storage needs to access the original object.
    // - The object needs to be renamed/copied in ConfigFactory and reloaded.
    // - All instances of the object need to be renamed.
    $this->configFactory->rename($prefix . $id, $config_name);
  }
  $config = $this->configFactory->getEditable($config_name);

  // Retrieve the desired properties and set them in config.
  $config->setData($this->mapToStorageRecord($entity));
  $config->save($entity->hasTrustedData());

  // Update the entity with the values stored in configuration. It is possible
  // that configuration schema has casted some of the values.
  if (!$entity->hasTrustedData()) {
    $data = $this->mapFromStorageRecords(array($config->get()));
    $updated_entity = current($data);

    foreach (array_keys($config->get()) as $property) {
      $value = $updated_entity->get($property);
      $entity->set($property, $value);
    }
  }

  return $is_new ? SAVED_NEW : SAVED_UPDATED;
}