LibreOffice creates zombie processes

Our Docker container for Xwiki (which uses more or less an equivalent Compose file as the one described on Docker Hub) is producing zombie processes.

I've checked the parent PID of these processes and it's the LibreOffice process which spawn but never wait for them. Our instance of xwiki is seldom used, so this is not becoming a problem (hence the issue is tagged minor) but each time soffice.bin spawn a child, a new zombie is created.

I've tried a simple fix. Using the embeded init process in Docker (tini), by simply adding a new line to my compose file (init: true). But it did not help, because the zombies are child spawned by soffice.bin which is a child of the main java process, so it seems that tini does not track zombies that far (surprising to me as it should be registered as a process reaper so even those "far fecthed" child should be reaped by it).

I guess a clean solution require more than just activating "tini". It might requires either having a more beeffy init system within the container (e.g. dumb-init or supervisord) or a fix in LibreOffice.