[keycloak-user] Prevent users from changing email address when email is used as username

[Ales Fuchs]

Hello,

We are using Keycloak version 4.8.3 and in our setting we have the option
"Email as username" switched on and "Edit username" switched off.

At the same time we need to let users to log in and change their name in
the account console. Once the name and surname is editable, email can be
changed too, which changes also the username.

The input with email can be hidden, but whoever knows how Keycloak works
can simply add this input and update the username.

Does anyone have any idea how updating of username can be prevented?

Best regards,
Ales Fuchs