class FieldInstanceOptionTranslation

class FieldInstanceOptionTranslation extends ProcessPluginBase {
  
  /**
   * {@inheritdoc}
   */
  public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
    [
      $type,
      $data,
    ] = $value;
    $data = unserialize($data);
    $property = $row->getSourceProperty('property');
    $option_key = $property == 0 ? 'off_label' : 'on_label';
    $translation = '';
    if (isset($data['settings']['allowed_values'])) {
      $allowed_values = $data['settings']['allowed_values'];
      switch ($type) {
        case 'boolean':
          if (isset($allowed_values[$property])) {
            $translation = $row->getSourceProperty('translation');
            break;

          }
          break;

        default:
      }
    }
    return [
      'settings.' . $option_key,
      $translation,
    ];
  }

}