I hope you will write this code better. The name bug-nest litteraly means here that this code is full of bad practices. These flaws were put there on purpose so that you can understand how to write better code.
You can start reading about the issues in the issues section.
They are going to make sure you avoid the same mistakes I did when I was younger. Trust me !
You can practice interfaces, or maybe dive straight into a framework like Spring boot, which is the route I'm going with for my students.
Some weird teacher called Mr. Toky trying to teach debugging and OOP at the same time in an innovative way. Keep in mind that trial and errors are necessary for innovation so this might not be enough to master even the basics for some people.
Let me know if this helps more than your typical : Animal, Shape, Person type of exercise from the 90s to learn about Object oriented programming.
Mail : toky@hei.school