Key point
Proof beats claims
Your repo is the proof. A recruiter should see the feature, run it, and understand your object model in a few minutes.
Do not submit only class diagrams or copied notes. Submit working code with a small, real feature.
Pick one feature
Choose a feature small enough to finish and large enough to show objects working together. Think hostel room booking, UPI expense split, canteen order billing, event registration, or library fine calculation.
Your feature should have 3 to 6 classes. It should show composition, interfaces, or clear SOLID choices from earlier lessons.