code: @BetaApi(
        "The surface for long-running operations is not stable yet and may change in the future.")
    public final OperationFuture<AsyncBatchAnnotateFilesResponse, OperationMetadata>
        asyncBatchAnnotateFilesAsync(List<AsyncAnnotateFileRequest> requests) {
  
      AsyncBatchAnnotateFilesRequest request =
          AsyncBatchAnnotateFilesRequest.newBuilder().addAllRequests(requests).build();
      return asyncBatchAnnotateFilesAsync(request);
    }
docs: Run asynchronous image detection and annotation for a list of generic files, such as PDF files,
  which may contain multiple pages and multiple images per page. Progress and results can be
  retrieved through the `google.longrunning.Operations` interface. `Operation.metadata` contains
  `OperationMetadata` (metadata). `Operation.response` contains `AsyncBatchAnnotateFilesResponse`
  (results).
  
  <p>Sample code:
  
  <pre><code>
  try (ImageAnnotatorClient imageAnnotatorClient = ImageAnnotatorClient.create()) {
  List&lt;AsyncAnnotateFileRequest&gt; requests = new ArrayList&lt;&gt;();
  AsyncBatchAnnotateFilesResponse response = imageAnnotatorClient.asyncBatchAnnotateFilesAsync(requests).get();
  }
  </code></pre>
  
  @param requests Individual async file annotation requests for this batch.
  @throws com.google.api.gax.rpc.ApiException if the remote call fails