Reading from the source code:

https://github.com/mozilla/pdf.js/blob/57d196e3497e77c81c19f852715ce79d9fb91492/src/display/annotation_layer.js#L2846

it appears to me it was not an intention to mark downloadManager as a required parameter in AnnotationLayerParameters:

https://github.com/mozilla/pdf.js/blob/57d196e3497e77c81c19f852715ce79d9fb91492/src/display/annotation_layer.js#L63

and AnnotationLayerBuilderOptions:

https://github.com/mozilla/pdf.js/blob/57d196e3497e77c81c19f852715ce79d9fb91492/web/annotation_layer_builder.js#L40

and it should be optional, similarly to accessibilityManager for example:

https://github.com/mozilla/pdf.js/blob/57d196e3497e77c81c19f852715ce79d9fb91492/web/text_layer_builder.js#L30

**Configuration:**
- PDF.js version: 2.11.174
- Is a browser extension: no

**What is the expected behavior? (add screenshot)**

`downloadManager` to be optional

**What went wrong? (add screenshot)**

`downloadManager` marked as required

Link to a viewer (if hosted on a site other than mozilla.github.io/pdf.js or as Firefox/Chrome extension):

* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
import {
  AnnotationBorderStyleType,
  AnnotationEditorType,
  AnnotationPrefix,
  AnnotationType,
  FeatureTest,
  LINE_FACTOR,
  shadow,
  unreachable,
  Util,
  warn,
} from "../shared/util.js";
import {
  DOMSVGFactory,
  getFilenameFromUrl,
  PDFDateString,
  setLayerDimensions,
} from "./display_utils.js";
import { AnnotationStorage } from "./annotation_storage.js";
import { ColorConverters } from "../shared/scripting_utils.js";
import { NullL10n } from "display-l10n_utils";
import { XfaLayer } from "./xfa_layer.js";
const DEFAULT_TAB_INDEX = 1000;
const DEFAULT_FONT_SIZE = 9;
const GetElementsByNameSet = new WeakSet();
function getRectDims(rect) {