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):

break;
              case "deleteContentForward":
                if (selectionStart === selectionEnd) {
                  selEnd += 1;
                }
                break;
            }
            
            event.preventDefault();
            this.linkService.eventBus?.dispatch("dispatcheventinsandbox", {
              source: this,
              detail: {
                id,
                name: "Keystroke",
                value,
                change: data || "",
                willCommit: false,
                selStart,
                selEnd,
              },
            });
          });
        }
        this._setEventListeners(
          element,
          elementData,
          [
            ["focus", "Focus"],
            ["blur", "Blur"],
            ["mousedown", "Mouse Down"],