'transfer app account to another smartphone

How can I transfer android app account created used AccountManager https://developer.android.com/reference/android/accounts/AccountManager to new smartphone?

I try it:

adb backup - this app has backup protection
Swift Backup - backup, then delete app, then restore - do not restore app account.

All solutions via exiting app or any sources or any ideas are suitable.

Smartphone may be rooted.

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Solution	Source