/usr/include/cinnamon-desktop/libcinnamon-desktop/ is in libcinnamon-desktop-dev 3.6.2-2.
This file is owned by root:root, with mode 0o755.
..
/usr/include/cinnamon-desktop/libcinnamon-desktop/cdesktop-enums.h
/usr/include/cinnamon-desktop/libcinnamon-desktop/gnome-bg-crossfade.h
/usr/include/cinnamon-desktop/libcinnamon-desktop/gnome-bg.h
/usr/include/cinnamon-desktop/libcinnamon-desktop/gnome-desktop-thumbnail.h
/usr/include/cinnamon-desktop/libcinnamon-desktop/gnome-desktop-utils.h
/usr/include/cinnamon-desktop/libcinnamon-desktop/gnome-installer.h
/usr/include/cinnamon-desktop/libcinnamon-desktop/gnome-pnp-ids.h
/usr/include/cinnamon-desktop/libcinnamon-desktop/gnome-rr-config.h
/usr/include/cinnamon-desktop/libcinnamon-desktop/gnome-rr-labeler.h
/usr/include/cinnamon-desktop/libcinnamon-desktop/gnome-rr.h
/usr/include/cinnamon-desktop/libcinnamon-desktop/gnome-wall-clock.h
/usr/include/cinnamon-desktop/libcinnamon-desktop/gnome-xkb-info.h