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):

this.container.style.visibility = hidden ? "hidden" : "visible";
        this.annotationStorage.setValue(this.data.id, {
          noView: hidden,
          noPrint: display === 1 || display === 2,
        });
      },
      print: event => {
        this.annotationStorage.setValue(this.data.id, {
          noPrint: !event.detail.print,
        });
      },
      hidden: event => {
        const { hidden } = event.detail;
        this.container.style.visibility = hidden ? "hidden" : "visible";
        this.annotationStorage.setValue(this.data.id, {
          noPrint: hidden,
          noView: hidden,
        });
      },
      focus: event => {
        setTimeout(() => event.target.focus({ preventScroll: false }), 0);
      },
      userName: event => {
        
        event.target.title = event.detail.userName;
      },
      readonly: event => {
        event.target.disabled = event.detail.readonly;
      },
      required: event => {