It looks like - when installing a JDK from java.sun.com - the autocomplete showing the available versions is gone, and there is now only a simple textbox, asking for a version.
That makes installing a JDK difficult (without knowing the exact JDK ID).
Here's a StackOverflow thread also mentioning the same problem: http://stackoverflow.com/questions/33760305/jenkins-configuring-jdk-only-textbox-and-auto-install-fails
There's nothing in the logs about this - is this a known regression?