I have an open-id client(SP) with Keycloak as IDP. I have siteminder as an external IDP with SAML protocol. When a user clicks on a link at Siteminder, he is authenticated and authorized using SAML assertion and the assertion is posted to the Keycloak IDP, so that user should be be able to access the client with open-id protocol without showing the login page. Is this possible i.e, can the external IDP with SAML can communicate with open-id client?