When you edit an item type there is this big image selector which allows you to select an image which is shown when creating a new item of that type.
It replaces the selected icon, which is very helpful for me to help the CMS moderators in visually recognize an item type.
But I use code first items and have no idea how to set this value.
The value ends up in the database as part of a JSON snippet.
When I select an image in the CMS and save, it shows, but after a rebuild it is gone again.
I would have expected something like this: