When using oauth2/openid connect authentication module/node, the client always authenticates to OpenID Connect provider using client_secret_post.
I was looking into our Social OIDC Node and came across https://bugster.forgerock.org/jira/browse/OPENAM-9779. As I'm aware when we are the OIDC Provider we support the private_key_jwt for our clients but not when we connect towards another provider. So the issue above could be easily included in our OIDC Node normally as we already created something likewise for our own OAuth 2.0 Client configurations.
- client_secret_jwt is supported
- tls_client_auth is supported
- self_signed_tls_client_auth is supported