}

    // Test run method with null DataService
    @Test
    public void test_run_nullDataService() {
        indexUpdater.dataService = null;
        try {
            indexUpdater.run();
            fail("Should throw FessSystemException");
        } catch (FessSystemException e) {
            assertEquals("DataService is null. IndexUpdater cannot proceed without a DataService instance.", e.getMessage());
        }
    }

- **StorageClient**: MinIO SDK, `storage://bucket/path`

### Services

- **UrlQueueService**: URL queue management (FIFO), duplicate detection
- **DataService**: Access result persistence, iteration
- Implementations: `UrlQueueServiceImpl`, `DataServiceImpl` (in-memory), `OpenSearchDataService` (persistent)

### Processing Pipeline

```

import org.codelibs.fess.crawler.client.CrawlerClientFactory;
import org.codelibs.fess.crawler.entity.OpenSearchAccessResult;
import org.codelibs.fess.crawler.extractor.ExtractorFactory;
import org.codelibs.fess.crawler.service.DataService;
import org.codelibs.fess.dict.DictionaryManager;
import org.codelibs.fess.ds.DataStoreFactory;
import org.codelibs.fess.exception.ContainerNotAvailableException;
import org.codelibs.fess.helper.AccessTokenHelper;

   * Example usage:
   *
   * {@snippet :
   * FluentFuture<RowKey> rowKeyFuture = FluentFuture.from(indexService.lookUp(query));
   * ListenableFuture<QueryResult> queryFuture =
   *     rowKeyFuture.transformAsync(dataService::readFuture, executor);
   * }
   *
   * <p>When selecting an executor, note that {@code directExecutor} is dangerous in some cases. See

   * Example usage:
   *
   * {@snippet :
   * ListenableFuture<RowKey> rowKeyFuture = indexService.lookUp(query);
   * ListenableFuture<QueryResult> queryFuture =
   *     transformAsync(rowKeyFuture, dataService::readFuture, executor);
   * }
   *
   * <p>When selecting an executor, note that {@code directExecutor} is dangerous in some cases. See
   * the warnings the {@link MoreExecutors#directExecutor} documentation.
   *