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):

if (!this.data.popupRef && this.hasPopupData) {
      this._createPopup();
    }
    this.container.classList.add("squigglyAnnotation");
    return this.container;
  }
}
class StrikeOutAnnotationElement extends AnnotationElement {
  constructor(parameters) {
    super(parameters, {
      isRenderable: true,
      ignoreBorder: true,
      createQuadrilaterals: true,
    });
  }
  render() {
    if (!this.data.popupRef && this.hasPopupData) {
      this._createPopup();
    }
    this.container.classList.add("strikeoutAnnotation");
    return this.container;
  }
}
class StampAnnotationElement extends AnnotationElement {