/usr/share/xsessions/openbox-kde.desktop is in openbox-kde-session 3.5.2-8+deb8u1.
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=KDE/Openbox
Comment=Use the Openbox window manager inside of the K Desktop Environment
Exec=/usr/bin/openbox-kde-session
TryExec=startkde
Icon=openbox
Type=Application
|