Collaboration project in Java Intellij

anybody doing the advanced java course tried to creating any portal system or other ambitious collaborative projects? I would like to collaborate and build something substantial to add to my portfolio. I already know the system will require a SQLdatabase too which as an almost essential skill as a developer specialising in Java. I imagine the system would be a suitable for full stack development instance so html css and JS will be useful competencies in the future for this project.
We can exchange emails or link up on github to share code. please don’t hesitate to get in touch if you need something to add to your C.V and want to learn together please get in touch.