I'm also seeing this. It also was working for me previously AFAIK. Tthe proximate cause is my well-intentioned change that uses HTTPS to access all artifact repos. The default for Maven Central before would have been HTTP. While it's a good idea to use HTTPS, it may run into complications.
I see: https://issues.sonatype.org/browse/MVNCENTRAL-377 https://issues.apache.org/jira/browse/INFRA-7363 ... which suggest that actually this isn't supported, and should return 404. Then I see: http://blog.sonatype.com/2012/10/now-available-ssl-connectivity-to-central/#.Uy7Yuq1_tj4 ... that suggests you have to pay for HTTPS access to Maven Central? But, we both seem to have found it working (even after the change above) and it does not return 404 now. The Maven build works, still, but if you look carefully, it's actually only because it eventually falls back to HTTP for Maven Central artifacts. So I think the thing to do is simply back off to HTTP for Maven Central only. That's unfortunate because there's a small but non-trivial security issue here in downloading artifacts without security. Any brighter ideas? I'll open a supplementary PR if so to adjust this.
