The upstream zkServer.sh server management script gives a nice way to control
settings (i.e. also whether to enable it or not), by having
JMXDISABLE="" or JMXDISABLE="false"
The systemd unit however *always* enables JMX. Of course one can override this,
would be nicer if there was a similar option that can be used
and all the creepy classes and weird java options (should that ever change) is
handled out of the box for the user.
This is the maintainer address of Debian's Java team
debian-j...@lists.debian.org for discussions and questions.