Referencing JAR configuration in subproject from root project

In simple, single project builds, I use a plugin to publish artifacts to releases in GitHub using the following configuration:

releaseAssets jar.destinationDirectory.files()

I now have a multi-project with artifacts produced by many of the subprojects, and I want to dynamically collect references to all of those artifacts, but I’m not able to figure out how to reference those files from the root project.

Could not get unknown property 'jar'

I’m sure it’s something simple, but I haven’t been able to find it yet. I appreciate the help.