Need to run automated tests against your Java app?
In order to run automated integration or functional tests, you need to spin up your application, together with all it's dependencies - that might include a database, a cache, etc.
You may still be doing this the old fashioned way: start MySQL separately, start Redis, then your application, and then run your tests. And you probably have these instructions documented in a team Wiki.
Perhaps you're doing it better: you have a few Dockerfiles, together with a Docker Compose file to spin up the application, and then you run your tests against the Dockerized version. Again, your Wiki probably tells your team how to setup Docker, build images, run Docker Compose, and your tests.