A default of 0 means that if you deploy two NixOS boxes with the default
configuration, the second will fail because the brokerId was already in
use. Using -1 instead tells it to pick one automatically at first start.
- add missing types in module definitions
- add missing 'defaultText' in module definitions
- wrap example with 'literalExample' where necessary in module definitions
JVMs exit with exit code 128+signal when receiving a (terminating)
signal. This means graceful termination of a JVM will result in 143, so
add that to `SuccessExitStatus` in systemd service unit.
