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):

const { pageWidth, pageHeight, pageX, pageY } = viewport.rawDims;
    if (!data.rect || this instanceof PopupAnnotationElement) {
      const { rotation } = data;
      if (!data.hasOwnCanvas && rotation !== 0) {
        this.setRotation(rotation, container);
      }
      return container;
    }
    const { width, height } = getRectDims(data.rect);
    
    
    const rect = Util.normalizeRect([
      data.rect[0],
      page.view[3] - data.rect[1] + page.view[1],
      data.rect[2],
      page.view[3] - data.rect[3] + page.view[1],
    ]);
    if (!ignoreBorder && data.borderStyle.width > 0) {
      container.style.borderWidth = `${data.borderStyle.width}px`;
      const horizontalRadius = data.borderStyle.horizontalCornerRadius;
      const verticalRadius = data.borderStyle.verticalCornerRadius;
      if (horizontalRadius > 0 || verticalRadius > 0) {
        const radius = `calc(${horizontalRadius}px * var(--scale-factor)) / calc(${verticalRadius}px * var(--scale-factor))`;
        container.style.borderRadius = radius;
      } else if (this instanceof RadioButtonWidgetAnnotationElement) {
        const radius = `calc(${width}px * var(--scale-factor)) / calc(${height}px * var(--scale-factor))`;
        container.style.borderRadius = radius;
      }
      switch (data.borderStyle.style) {
        case AnnotationBorderStyleType.SOLID: