I've used 5.2.0 before and then decided to migrate to 6.1.0
What I found is that project.components.java is updated with shadowJar configurations here:
https://github.com/johnrengelman/shadow/blame/b3677a26c706aec9aa7b035b9d36a091523aff97/src/main/groovy/com/github/jengelman/gradle/plugins/shadow/ShadowJavaPlugin.groovy#L56

So, I can't use maven-publish to publish only raw, unshadowed JARs: publication JAR conflict happens.
Please, make adding shadowJar things to java software component optional: I'd enable this option in project config.
Thank you!