https://developers.google.com/android/reference/com/google/android/gms/auth/api/accounttransfer/AccountTransfer?authuser=1
AccountTransfer | Google Play services | Google for Developers
google play servicesdevelopers
https://developers.google.cn/android/reference/com/google/android/gms/auth/api/accounttransfer/package-summary
com.google.android.gms.auth.api.accounttransfer | Google Play services | Google for Developers
google androidauth apiplay servicesgms