can't kill java process in alpine image

I'm drawing blanks here, we switch from `adoptopenjdk/openjdk13:debian` to `adoptopenjdk/openjdk13:alpine`, and I'm unable to kill my `java` process anymore ...
Both SIGTERM and SIGINT are ignored by the java process, but SIGKILL works, and SIGQUIT also actually gives a thread dump.

to exclude it being some issue with `bash` vs busybox `sh` I also installed `bash` on the alpine image and used that, didn't make any difference...

we do actually have a `Runtime.getRuntime()::addShutdownHook` registered.

note; also tested with jdk11, just to be sure