Given your comment, I think we are talking about two different things: this plugin allows people to:
- either use a pre-filled combo, select JDK, and have Jenkins automatically download it from oracle.com.
- or the other way (which should the strongly recommended one ) is to do it very similarly, but define the JDK name, a custom URL (usually pointing to some internal webserver, ideally some binary repository like Nexus or Artifactory where you'll have uploaded some jdk.zip yourself), and then from a Jenkins user standpoint it looks absolutely the same.
The huge difference is that using the latter strategy you don't risk to block your whole build infra because your Internet access has a temporary network glitch, or a more durable stop if oracle.com starts banning your IP, after getting annoyed that you keep downloading the same thing dozens or hundreds of times a day from their servers (bandwidth does cost some money ).
I hope this clarifies.
 Unfortunately, I didn't check, but I don't think this is currently correctly documented. We should be able to fix this soon I hope. (PRs welcome, though . Happy to help anyone doing this).