I can't think of an easy solution here. If it were a Java function or Java class question type you could customise the question and add code to the template to replace the student's submitted file with a (renamed) copy of an author-supplied file. But this sounds like a Java program question type where the template is just {{ STUDENT_ANSWER }} and I can't see how to tweak that to do such things.
I don't think I've ever tried adding a support file that's named the same as the student file, but I should think you're right that the question will be marked wrong. You could try, just to be sure, though.
If you're really keen and have sufficient CodeRunner knowledge, you could edit the question to use instead a Python script of the sort used in the multilanguage question type: that could set up whatever environment you wanted before compiling and running the student code. But unless this is a very large class, that's probably not worth the effort.