Hey Andrew,
Sorry for the delayed reply here. This is an overzealous check that the group when publishing plugins cannot contain “gradle”.
The whole Gradle team is traveling internationally this week, so support will be delayed unfortunately. I will notify responsible folks of this request, but the quickest resolution will be to use something else other than “gradle” in the group ID when publishing for now.
Don’t be afraid to use the “further help” form suggested by @lingocoder which sends support folks an email.
Cheers,
Eric