Improve details for user error events in SAML protocol endpoints

[thomasdarimont]

Description

Currently, Keycloak administrators have a hard time analyzing a problem when an error occurs during SAML protocol interactions, since most of the relevant information is either only logged to the console (on debug) or does not contain helpful information. Sometimes Keycloak administrators don't have direct access to the server logs and have to rely on the information shown in the User Events view in the admin UI.

However, even if those errors are recorded as user events they often lack the necessary details / reason, why a concrete problem occured.

This issue proposes to add appropirate reason notes as details to the user error event, to help administrators to investigate the cause of a problem.

Discussion

No response

Motivation

Sometimes the error codes alone are not helpful when trouble shooting a protocol usage related problem.
Administrators should be able to see a problem caused by protocol misuse by looking at the user events where the information is available.

Details

My suggestion is to walk through the SAML protocol endpoints and inspect the debug log for error handlers. When an error event is registered, we can probably add some more helpful information as Details.REASON to the event details of the current user event.