/usr/share/xsessions/cinnamon.desktop is in cinnamon-common 3.6.7-8ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 | [Desktop Entry]
Name=Cinnamon
Comment=This session logs you into Cinnamon
Exec=cinnamon-session-cinnamon
TryExec=/usr/bin/cinnamon
Icon=
Type=Application
|