code: public List<Blob> batchUpdateIterable(String bucketName, String blobName1, String blobName2) {
      // [START batchUpdateIterable]
      Blob firstBlob = storage.get(bucketName, blobName1);
      Blob secondBlob = storage.get(bucketName, blobName2);
      List<BlobInfo> blobs = new LinkedList<>();
      blobs.add(firstBlob.toBuilder().setContentType("text/plain").build());
      blobs.add(secondBlob.toBuilder().setContentType("text/plain").build());
      List<Blob> updatedBlobs = storage.update(blobs);
      // [END batchUpdateIterable]
      return updatedBlobs;
    }
docs: [VARIABLE "my_blob_name2"]