**As** a user
**I want OpenProject to** preserve my authentication provider identity when I log in though another provider Begin of the deletion
**so that** I see which external accounts are connected to my OpenProject accountEnd of the deletion

**Acceptance criteria**

* Begin of the insertionNothing should break for users. "nothing" is:

* SSO log in/sign up using SAML

* SSO log in/sign up using OpenIDConnect 


End of the insertion Begin of the deletion User can see which external accounts are connected to its OpenProject account.


End of the deletion **Technical notes**

* Now:

* `users.identity_url` column is used to store `#{auth_provider_slug}:#{auth_provier_user_id}`. And it gets overwritten every time user logs in with another provider.

* Should be:

* `users.identity_url` data moved to a separate table(e.g. `user_auth_provider_links(id, user_id, auth_provider_id, external_id)`

* when user logs in with authentication provider

* then application looks for existing link

* uses it if there is one

* creates new one if there is none

* API `users.identity_url`

* should be marked as deprecated

* on update should change existing link if possible and create a new one otherwise.

* should return last updated link


**Out of scope**

* Begin of the insertionUI showing all linked accountsEnd of the insertion Begin of the deletion <br>End of the deletion