No way to set specific refresh token?

Consider this scenario:

1. Users logs in for the first time in my Qt app (OAuth 2.0 - QtNetworkAuth).
2. I save refresh token AND access token to DB.
3. Users restarts app and wants to continue, refresh token and access token are loaded from DB.
4. I want to set these existing tokens to my QOAuth2AuthorizationCodeFlow instance. How??? I only found method to set access token, which is in fact useless without method to set refresh token too!

On some online APIs, refresh token do not expire, ever. So when user of your app starts it on the other day, he does not have to grant OAuth permissions again, the stored refresh token is simply used to gain new access token (without user interaction of course), so that user does not have to grant permissions again.

Add a way to set my specific refresh token, if there is not one. This is actually quite a blocker for all use cases where refresh token is not rotated by the API after its use.