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):

#polylines = [];
  constructor(parameters) {
    super(parameters, { isRenderable: true, ignoreBorder: true });
    this.containerClassName = "inkAnnotation";
    
    
    this.svgElementName = "svg:polyline";
    this.annotationEditorType = AnnotationEditorType.INK;
  }
  render() {
    this.container.classList.add(this.containerClassName);
    
    
    const data = this.data;
    const { width, height } = getRectDims(data.rect);
    const svg = this.svgFactory.create(
      width,
      height,
       true
    );
    for (const inkList of data.inkLists) {
      
      
      
      
      let points = [];
      for (const coordinate of inkList) {
        const x = coordinate.x - data.rect[0];