I tried to run some tests in Mattermost Cloud to evaluate Mattermost Enterprise Edition.
After setting up OIDC (OpenID Connect), I found that Mattermost tends to use the user’s email prefix as the username instead of the preferred_username provided in the OIDC Profile.
While the OpenID Connect documentation does not explicitly mention if there is any possibility of configuring specific attribute for username, may I know if you are open to create a suggestion in Mattermost Uservoice?
However, using the preferred_username claim as a username is part of the OIDC specification, so please consider a more standardized implementation of OIDC.
Claim Name: preferred_username
Claim Description: Shorthand name by which the End-User wishes to be referred to
Got it and thanks for the details. I am putting the link out here for reference purposes for other users who are also interested with the same implementation of OpenID Connect: