Project jmh-core's maven file references a maven repository under http://download.java.net/maven/2
This does not work. Recent Maven versions require https. Additionally the above URL returns HTTP 404, and the build passes just fine without it. This repository reference should be removed.

Additionally, the main POM file still references the old mercurial repository. That repository is no longer updated, and the POM file should be updated to point to github.