JDK11 required: OpenTracks upgrades to API31

The upcoming release of OpenTracks upgrades to API31 and this requires compiling with JDK11. However, I don't know how to extend the build metadata to include this.

This recipe is required according to https://forum.f-droid.org/t/f-droid-support-for-sdk31-android/14172/3

sudo:
  - apt-get update || apt-get update
  - apt-get install -t stretch-backports openjdk-11-jdk-headless openjdk-11-jre-headless
  - update-alternatives --auto java

If I understood it correctly, this sudo: belongs to a build entry: https://f-droid.org/en/docs/Build_Metadata_Reference/#Builds But the build entries are automatically created by F-Droid using AutoUpdateMode.

So, how can I trigger the installation of JDK11 for every new release? I might also just not have understood the file format...