How to use UnityToolbag SortinglayerExposed?

I’m building a 2D game. I imported some fbx objects into my project. These objects don’t show sorting layer field. However, a solution exists. But i can’t figure out how to use it. Are there any step by step instructions on how to use it?

Create a folder “Editor” in project assets. Add SortingLayerExposedEditor and SortingLayerExposedHelper to this folder. Attach SortingLayerExposed to each game object you want to expose. Wonder what unity achieves by not providing this as built in feature.