Senior Java Interview: Bug Fix in a Generic Repository

Your team has built a generic repository used by several Spring Boot services for caching reference data before it’s persisted.

A teammate recently tried to reuse it for a new feature and hit a compilation error.

You’re reviewing their pull request.

The new feature does this:

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A common misconception is:

"AdminUser extends User, so List<AdminUser> should extend List<User>."

That's not how Java generics work. Generics are invariant.