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 storedData = storage.getValue(id, {
        value: this.data.fieldValue,
      });
      let textContent = storedData.value || "";
      const maxLen = storage.getValue(id, {
        charLimit: this.data.maxLen,
      }).charLimit;
      if (maxLen && textContent.length > maxLen) {
        textContent = textContent.slice(0, maxLen);
      }
      let fieldFormattedValues =
        storedData.formattedValue || this.data.textContent?.join("\n") || null;
      if (fieldFormattedValues && this.data.comb) {
        fieldFormattedValues = fieldFormattedValues.replaceAll(/\s+/g, "");
      }
      const elementData = {
        userValue: textContent,
        formattedValue: fieldFormattedValues,
        lastCommittedValue: null,
        commitKey: 1,
        focused: false,
      };
      if (this.data.multiLine) {
        element = document.createElement("textarea");
        element.textContent = fieldFormattedValues ?? textContent;
        if (this.data.doNotScroll) {
          element.style.overflowY = "hidden";
        }