Gradle docs say that publishing features should just work, but for me it doesn't, Sonatype Central Portal is giving me bogus "Dependency version information is missing" errors. So how can I actually disable publishing of custom features? (As I only need to be able to build them locally.)

This example shows how to skip publishing of test fixtures variants, it is the same for other variants: https://docs.gradle.org/current/userguide/java_testing.html#ex-disable-publishing-of-test-fixtures-variants

Thanks, I'll give that a try. I continue to forget that test fixtures are implemented via feature variants.