gnome-packagekit-session software package provides Transitional package (gnome-packagekit-session -> gnome-software), you can install in your Debian 9 (Stretch) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install gnome-packagekit-session
gnome-packagekit-session is installed in your system.
Make ensure the gnome-packagekit-session package were installed using the commands given below,
$ sudo dpkg-query -l | grep gnome-packagekit-session *
You will get with gnome-packagekit-session package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Old Libraries |
| Package | gnome-packagekit-session |
| Version | 3.22.1-1 |
| Description | Transitional package (gnome-packagekit-session -> gnome-software) |
| Sub Section | Oldlibs |