Likely bug: oauth2_client USERNAME = email issue

HI,

If you registering new user through oauth2 you should be able to set strict username for example “username part of the email attribute”
It is described in Config Cheat Sheet - Docs
But all I got is empty Username field which you can fill anything.
My app.ini config:

[oauth2_client]
USERNAME = email

[service]
REGISTER_EMAIL_CONFIRM = true
ENABLE_NOTIFY_MAIL = false
DISABLE_REGISTRATION = false
ALLOW_ONLY_EXTERNAL_REGISTRATION = true
ENABLE_CAPTCHA = false
REQUIRE_SIGNIN_VIEW = false
DEFAULT_KEEP_EMAIL_PRIVATE = false
DEFAULT_ALLOW_CREATE_ORGANIZATION = false
DEFAULT_ENABLE_TIMETRACKING = true

Is my config wrong or is it bug? it looks to me like a bug.
go-gitea 1.14.1

/Domantas

Looks this feature not yet in PROD