Project for JAVA

The services of a Java developer are required. I am looking for an interesting Java project or a new one. Perhaps it is a site with a database, a game, perhaps a desktop application, etc. They plan to use it for the coursework, after the diploma, so there should be a capacious project. Since the topic was not chosen, I decided to find a ready-made project, thereby you will not need to write anything from scratch, only some additions are possible along the way.
That is, in the end, only three points are important: the language of JAVA, a capacious project, an interesting topic of the project (that is, conditionally not an online furniture store, etc., which is usually done by everyone).