New Java autograder

Jonatan Schroeder has implemented a new Java autograder for PrairieLearn. While courses will always be able to use custom autograders, this provides a robust and secure reference implementation that courses can use directly, or as the basis for their own code.

To test out the new autograder, try the demo/autograder/java/square and demo/autograder/java/helloWorld questions in the example course.

The autograder is based on JUnit 5 tests, and supports individual JUnit 3/4/5 test classes, as well as the use of question-level or course-level Java libraries.

The new autograder is included by default in the grader-java docker image. To take advantage of it you can edit your question's info.json file to include:

"externalGradingOptions": {
    "image": "prairielearn/grader-java",
    "entrypoint": "autograder.sh"
}

To read more about new grader features you can check out the documentation.