> I know you will say, this is all fault of whoever made this crap project, or my fault for not fixing it. However this was my experience, and it has been similar every time in my life that I had to touch some java project

Yeah that’s a crap project. My experience was always that mvn install / ./gradlew run will just work. On all three OSs. And if I happen upon a decade old random jar file, and run java -jar something.jar, it will just work in the great majority of time. I think no other platform has it this smooth.