Logging OIDC response?

[Jim Tomlinson]

I'm obviously looking in all the wrong docs; a pointer would be appreciated.
I'm trying to diagnose an issue an OIDC client is having with our Shib 4.1.0 IdP's auth response (they're receiving a multi-value claim as a space-separated list, rather than a JSON array, and yeah, I've specified "asArray="true" in the AttributeEncoder element). I'm having problems getting the IdP to fully log that response, unencrypted. I've cranked pretty much everything up to TRACE in logback.xml (including net.shibboleth.oidc.attribute.transcoding, net.shibboleth.oidc.jwk.support, net.shibboleth.oidc.security.jwt.claims.impl, net.shibboleth.oidc.metadata.impl and net.shibboleth.oidc.metadata.keyinfo.ext.impl.provider), to no avail.
Any pointers on how to accomplish that? Thanks.
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Jim Tomlinson (he/him)
Software Engineer, Identity and Access Management
UW Information Technology
University of Washington