materialVariety property
To add your own resources, refer to the assets folder structure inside this package. If your resources includes sparate materials for each color, add to path like this: "assets/your_materials_name/black/king.png" (or /white/ for white pieces). and same for all other pieces. If you've simple and fillable png recourses, simply add them in "assets/your_materials_name/bishop.png" path.
Implementation
String? materialVariety;