That looks easy enough: search the net in which package they are, copy the dependency into your pom.xml and here you go!
But I didn't didn't anything that I could use as a dependency.
Not much of a surprise, other people had the same problem, and solutions can found here https://stackoverflow.com/a/29270114/4142984 in combination with https://stackoverflow.com/a/15692230/4142984 .
In other words, those solutions suggest to get the jar manually and hard-link it in you build-path. It worked, though.
But isn't maven supposed to do that?
Question is: what did I miss, to tell maven to do this.
And I'm using maven with eclipse, just in case this would make a difference.