Tomcat9 based Debian package is not starting at boot time

See https://forum.xwiki.org/t/shutting-down-tomcat-with-errors-the-web-application-xwiki-created-a-threadlocal/6950/3. `service` start tomcat just fine but systemctl seems to have problem with the link in /etc/systemd/system/tomcat9.service.d.