code: public function find(string $identifier): ?OptInTokenInterface
      {
          /** @var OptInModel $adapter */
          $adapter = $this->framework->getAdapter(OptInModel::class);
  
          if (!$model = $adapter->findByToken($identifier)) {
              return null;
          }
  
          return new OptInToken($model, $this->framework);
      }
docs: {@inheritdoc}