Qt network request auto adding unexpected question mark - c++

Question

I am trying to send http POST request. Here is code snippets:
const QUrl URL("https://httpbin.org/post");
QNetworkRequest req(URL);
req.setHeader(QNetworkRequest::ContentTypeHeader, "application/x-www-form-urlencoded");
QUrlQuery urlQuery;
urlQuery.addQueryItem ("username", username);
urlQuery.addQueryItem ("password", password);
QUrl params;
params.setQuery (urlQuery);
mNetReply = mNetMan->post(req, params.toEncoded());
and here is the response output:
QJsonObject({"args":{},"data":"","files":{},"form":{"?username":"xyz","password":"xyz"},"headers":{"Accept-Encoding":"gzip, deflate","Accept-Language":"en-US,*","Connection":"close","Content-Length":"28","Content-Type":"application/x-www-form-urlencoded","Host":"httpbin.org","User-Agent":"Mozilla/5.0"},"json":null,"origin":"*.*.*.*","url":"https://httpbin.org/post"})
My problem is , qt automatically adding a ? mark in first queryItem.

Answer 1

For what it's worth still, because an answer was not given:
Don't use the conversion to a QUrl, using the QUrlQuery directly solved the problem for me.
urlQuery.toString(QUrl::FullyEncoded).toUtf8()
in stead of
params.toEncoded()
Total snippet updated:
const QUrl URL("https://httpbin.org/post");
QNetworkRequest req(URL);
req.setHeader(QNetworkRequest::ContentTypeHeader, "application/x-www-form-urlencoded");
QUrlQuery urlQuery;
urlQuery.addQueryItem ("username", username);
urlQuery.addQueryItem ("password", password);
mNetReply = mNetMan->post(req, urlQuery.toString(QUrl::FullyEncoded).toUtf8());