/usr/share/icinga2/include/ is in icinga2-common 2.6.0-2+deb9u1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/icinga2/include/command-icinga.conf
/usr/share/icinga2/include/command-nscp-local.conf
/usr/share/icinga2/include/command-plugins-manubulon.conf
/usr/share/icinga2/include/command-plugins-windows.conf
/usr/share/icinga2/include/command-plugins.conf
/usr/share/icinga2/include/hangman
/usr/share/icinga2/include/itl
/usr/share/icinga2/include/manubulon
/usr/share/icinga2/include/nscp
/usr/share/icinga2/include/plugins
/usr/share/icinga2/include/plugins-contrib
/usr/share/icinga2/include/plugins-contrib.d/
/usr/share/icinga2/include/plugins-contrib.d/databases.conf
/usr/share/icinga2/include/plugins-contrib.d/hardware.conf
/usr/share/icinga2/include/plugins-contrib.d/icingacli.conf
/usr/share/icinga2/include/plugins-contrib.d/ipmi.conf
/usr/share/icinga2/include/plugins-contrib.d/logmanagement.conf
/usr/share/icinga2/include/plugins-contrib.d/metrics.conf
/usr/share/icinga2/include/plugins-contrib.d/network-components.conf
/usr/share/icinga2/include/plugins-contrib.d/network-services.conf
/usr/share/icinga2/include/plugins-contrib.d/operating-system.conf
/usr/share/icinga2/include/plugins-contrib.d/storage.conf
/usr/share/icinga2/include/plugins-contrib.d/virtualization.conf
/usr/share/icinga2/include/plugins-contrib.d/vmware.conf
/usr/share/icinga2/include/plugins-contrib.d/web.conf
/usr/share/icinga2/include/windows-plugins