What happens if `equals()` is not overridden in a custom class?
If `equals()` is not overridden, Java will throw a `NullPointerException` when comparing objects for equality.
I'm a bit disappointed, as no exception is thrown by default; instead, the reference comparison from `Object` is used.
Can you explain how the `Object` classâ€™s `equals()` method works if not overridden?