Snapshots for Groovy 4 are now at https://repository.apache.org/content/repositories/snapshots (under org/apache/groovy). Older snapshots remain at jcenter for the time being but won't be kept up to date there. The download page is updated accordingly. The build is via the ASF Jenkins infrastructure rather than teamcity. Moving snapshots for earlier versions is still a work in progress.
Cheers, Paul.
