If a project contains dependencies with the same module name (which is valid according to https://stackoverflow.com/a/46573805/14731) then maven-compile-plugin invokes `javac` with a modulepath containing dependencies in an (apparently) arbitrary order. If I place the project in one directory, I get one order. If I place the project in another directory, I get another order. This is 100% reproducible across multiple runs, across different computers.
I suspect that somewhere deep inside the code someone is using `HashMap` which is leading to undefined iteration order depending on the path being used.