/etc/icinga2/ is in icinga2-common 2.4.1-2ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/etc/icinga2/conf.d/
/etc/icinga2/conf.d/app.conf
/etc/icinga2/conf.d/apt.conf
/etc/icinga2/conf.d/commands.conf
/etc/icinga2/conf.d/downtimes.conf
/etc/icinga2/conf.d/groups.conf
/etc/icinga2/conf.d/hosts.conf
/etc/icinga2/conf.d/notifications.conf
/etc/icinga2/conf.d/satellite.conf
/etc/icinga2/conf.d/services.conf
/etc/icinga2/conf.d/templates.conf
/etc/icinga2/conf.d/timeperiods.conf
/etc/icinga2/conf.d/users.conf
/etc/icinga2/constants.conf
/etc/icinga2/features-available/
/etc/icinga2/features-available/api.conf
/etc/icinga2/features-available/checker.conf
/etc/icinga2/features-available/command.conf
/etc/icinga2/features-available/compatlog.conf
/etc/icinga2/features-available/debuglog.conf
/etc/icinga2/features-available/gelf.conf
/etc/icinga2/features-available/graphite.conf
/etc/icinga2/features-available/icingastatus.conf
/etc/icinga2/features-available/livestatus.conf
/etc/icinga2/features-available/mainlog.conf
/etc/icinga2/features-available/notification.conf
/etc/icinga2/features-available/opentsdb.conf
/etc/icinga2/features-available/perfdata.conf
/etc/icinga2/features-available/statusdata.conf
/etc/icinga2/features-available/syslog.conf
/etc/icinga2/features-enabled/
/etc/icinga2/icinga2.conf
/etc/icinga2/init.conf
/etc/icinga2/pki/
/etc/icinga2/repository.d/
/etc/icinga2/repository.d/README
/etc/icinga2/scripts/
/etc/icinga2/scripts/mail-host-notification.sh
/etc/icinga2/scripts/mail-service-notification.sh
/etc/icinga2/zones.conf
/etc/icinga2/zones.d/
/etc/icinga2/zones.d/README