Jenkins, Perforce and Multibranch, how to set up automatic branch detecting?

I'm setting up Jenkins with Pipeline (former Workflow) and trying to configure Multibranch. All documentation I find is about git and svn, but I'm stuck with using Perforce. I have installed all plugins, including p4 (the new Perforce plugin). Setting up a Multibranch job, I'm provided with a dropdown list under Branch Sources called Add source, with only the item called Single repository & branch. If selecting this, here is the description:

Allows a single, fixed branch of some repository to be configured. Not normally used, as it does not allow branches to be detected automatically. Might be used, for example, if you want to build all branches of one repository, and the master branch of a special clone.

For me, automatic detection of branches is essential. What am I missing?