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):

for (const option of this.data.options) {
      const optionElement = document.createElement("option");
      optionElement.textContent = option.displayValue;
      optionElement.value = option.exportValue;
      if (storedData.value.includes(option.exportValue)) {
        optionElement.setAttribute("selected", true);
        addAnEmptyEntry = false;
      }
      selectElement.append(optionElement);
    }
    let removeEmptyEntry = null;
    if (addAnEmptyEntry) {
      const noneOptionElement = document.createElement("option");
      noneOptionElement.value = " ";
      noneOptionElement.setAttribute("hidden", true);
      noneOptionElement.setAttribute("selected", true);
      selectElement.prepend(noneOptionElement);
      removeEmptyEntry = () => {
        noneOptionElement.remove();
        selectElement.removeEventListener("input", removeEmptyEntry);
        removeEmptyEntry = null;
      };
      selectElement.addEventListener("input", removeEmptyEntry);
    }
    const getValue = isExport => {
      const name = isExport ? "value" : "textContent";
      const { options, multiple } = selectElement;
      if (!multiple) {
        return options.selectedIndex === -1