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📜 WAYPOINT LESSON

Checkpoint: Object Contracts

⭐⭐ intermediate⏳ 15 min read📍 Lesson 66 of 180

Graded checkpoint: repair a broken value class and count distinct settings correctly.

Checkpoint — object contracts

You can now: distinguish identity from equality, pair equals with hashCode, and build immutable classes that do not leak mutability. Prove it by fixing a class whose hash contract and API boundaries are both broken.