Isn't the recommended way of distributing Java applications nowadays to bundle a custom JRE with it? Wasn't project jigsaw especially created to be able to just bundle libraries and/or classes the application requires instead of the whole JRE?
The distributions that matter here are for the JDK, which simply provides the "full" Java runtime along with developer tools such as javac and jlink.
sudo apt-get install openjdk-8-jre-headless -y on ubuntu. Works fine with UniFi Controller. (what do you think they use on the cloud key?)