I removed this specially in this commit
https://github.com/hhru/subscribe/commit/82f2be477f083086646dde62cdd267e5bbc31342
Maven will compile, but with warnings.
Otherwise, I'll need to change README.md every time I'm making release. And for sure I'll forget do this sometimes. It's better to provide a bit incomplete information, than outdated (wrong).
Here I need to provide groupId and artifactId.