Spark's MLLib states that https://github.com/fommil/netlib-java is a dependency.
However, this repo has been removed from github (the above link is dead). Google's cached version of the pages is still there, and there is a note that the library would be discontinued due to lack of funding.
Is the library no longer maintained? Where is the upstream branch now (I can see a few forks in github)? The author, Sam Halliday has moved most of his projects to GitLab but the repo doesn't appear to exist there.
I've found the official one here: https://gitlab.com/fommil/attic/tree/master/netlib-java
It's in the attic project which reads "Old mothballed projects that I'm not maintaining anymore"