### Steps to reproduce

* Begin of the insertionCreate a new "custom" OpenID Connect providerEnd of the insertion Begin of the deletion Not sure how to reproduce todayEnd of the deletion

* Begin of the insertionChoose a name

* Don't provide a metadata URL

* LookEnd of the insertion Begin of the deletion thisEnd of the deletion at Begin of the insertionthe form asking youEnd of the insertion Begin of the deletion least affected old installations of OpenProject that converted from OIDC providers pre-15.0.0End of the deletion to Begin of the insertionfill provider metadataEnd of the insertion Begin of the deletion post 15.0.0End of the deletion


### What is the buggy behavior?

* Begin of the insertionThe form is prefilled withEnd of the insertion Begin of the deletion `OpenIDConnect::Providers::SetAttributesService` setsEnd of the deletion the Begin of the insertion**issuer** being set to the OpenProject instanceEnd of the insertion Begin of the deletion OP rootEnd of the deletion URL Begin of the deletion as a default value for `issuer`End of the deletion


### What is the expected behavior?

* The issuer should be Begin of the insertionleft empty, like everythingEnd of the insertion Begin of the deletion a URL pointing towards the IDP, not towards OpenProject itself. This value will never be a good default.

* Unless somethingEnd of the deletion else Begin of the insertiontooEnd of the insertion Begin of the deletion prevents this, just don't set any default for the issuer thereEnd of the deletion


###

### Environment information

**OpenProject version**

15.0.0 - 17.9.0