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):

target.setAttribute("maxLength", charLimit);
              let value = elementData.userValue;
              if (!value || value.length <= charLimit) {
                return;
              }
              value = value.slice(0, charLimit);
              target.value = elementData.userValue = value;
              storage.setValue(id, { value });
              this.linkService.eventBus?.dispatch("dispatcheventinsandbox", {
                source: this,
                detail: {
                  id,
                  name: "Keystroke",
                  value,
                  willCommit: true,
                  commitKey: 1,
                  selStart: target.selectionStart,
                  selEnd: target.selectionEnd,
                },
              });
            },
          };
          this._dispatchEventFromSandbox(actions, jsEvent);
        });
        
        
        element.addEventListener("keydown", event => {
          elementData.commitKey = 1;