Why the .deb package asks for a java8-runtime-headless dependency instead of openjdk-8-jre-headless where you do not need to use ppa to use?
Avoid using ppa packages please change this
use openjdk-8-jre-headless as dependency instead of java8-runtime-headless that only exists in a ppa
Packages providing java8-runtime-headless
default-jre-headless
Standard Java or Java compatible Runtime (headless)
openjdk-8-jre-headless
OpenJDK Java runtime, using Hotspot JIT (headless)
https://packages.debian.org/stretch/java8-runtime-headless
why not use the package that is in the official debian repository and its derivatives? choosing a ppa is a serious mistake that should never happen!