class FieldBundle

class FieldBundle extends ProcessPluginBase implements ContainerFactoryPluginInterface {
  
  /**
   * The migrate lookup service.
   *
   * @var \Drupal\migrate\MigrateLookupInterface
   */
  protected $migrateLookup;
  
  /**
   * Constructs a ProcessField plugin.
   *
   * @param array $configuration
   *   The plugin configuration.
   * @param string $plugin_id
   *   The plugin ID.
   * @param mixed $plugin_definition
   *   The plugin definition.
   * @param \Drupal\migrate\MigrateLookupInterface $migrate_lookup
   *   The migrate lookup service.
   */
  public function __construct(array $configuration, $plugin_id, $plugin_definition, MigrateLookupInterface $migrate_lookup) {
    parent::__construct($configuration, $plugin_id, $plugin_definition);
    $this->migrateLookup = $migrate_lookup;
  }
  
  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration = NULL) {
    return new static($configuration, $plugin_id, $plugin_definition, $container->get('migrate.lookup'));
  }
  
  /**
   * {@inheritdoc}
   */
  public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
    [
      $entity_type,
      $bundle,
    ] = $value;
    $lookup_result = NULL;
    // For comment entity types get the destination bundle from the
    // d7_comment_type migration, if it exists.
    if ($entity_type === 'comment' && $bundle != 'comment_forum') {
      $value = str_replace('comment_node_', '', $bundle);
      $migration = 'd7_comment_type';
      $lookup_result = $this->migrateLookup
        ->lookup($migration, [
        $value,
      ]);
      $lookup_result = empty($lookup_result) ? NULL : reset($lookup_result[0]);
    }
    return $lookup_result ? $lookup_result : $bundle;
  }

}