Thanks for the info. If i read correct, the non-systemd dependend tomcat9
Package might be available only in buster-backports.
Its strange to me, that the fixed version 9.0.16-5 has been
uploaded in June 2019 to experimental already according to the mails
but according to the web-page is not yet available. But I have to admit,
that I also don't understand how this bug/upload/ftp process works
on Debian at all.