How can I tell state of checkbox in Google Docs via api?

If I create a Google document with a checklist, how do I tell whether an item is checked or unchecked? When I diff the document json, it is the same in either state (except for revision number).

Starting with a blank document, sample code to create a checkbox:

    List<Request> requests = new ArrayList<>();  
    //Checkbox
    requests.add(new Request().setInsertText(new InsertTextRequest()
            .setText("\n\n")
            .setLocation(new Location().setIndex(1))));
    requests.add(new Request().setInsertText(new InsertTextRequest()
            .setText("MARK\n")
            .setLocation(new Location().setIndex(2))));
    requests.add(new Request().setCreateParagraphBullets(
            new CreateParagraphBulletsRequest()
                    .setRange(new Range()
                            .setStartIndex(2)
                            .setEndIndex(3))
                    .setBulletPreset("BULLET_CHECKBOX")));

    BatchUpdateDocumentRequest batchUpdateDocumentRequest = new BatchUpdateDocumentRequest();
    BatchUpdateDocumentResponse response = service.documents().batchUpdate(documentId, batchUpdateDocumentRequest.setRequests(requests)).execute();

`

I can click or unclick the checkbox, but the document remains unchanged when I look at it via:

Document document = service.documents().get(documentId).execute(); l.info(document.toPrettyString());

Anyone have experience with this?