Incorrect Clazy warning "Call to temporary is a no-op"

I have class JsonParser:

class JsonParser : public QObject
{
    Q_OBJECT
protected:
    QJsonDocument _document;
};

In my subclass JsonSpecialistParser : public JsonParser, I have methods of the form

void JsonSpecialistParser::task()
{
    QJsonObject newRoot;
    //...
    _document.setObject(newRoot);
}

 The line containing _document.setObject(newRoot) gets the Clazy warning:

Call to temporary is a no-op: QJsonDocument::setObject [clazy-writing-to-temporary]

I believe this is incorrect as _document is not a temporary and setObject operates on it directly.