Beat Primitive Obsession

Introduce a value object in Solution: - static class Email with constructor (String raw) that validates: exactly one '@', non-empty local part and domain, domain contains a '.' after the '@'. Invalid → IllegalArgumentException. Store a normalized (trimmed, lowercased) final field value with getter value(). - static List<String> uniqueEmails(List<String> rawList) — parses each into Email (invalid ones skipped) and returns distinct normalized values, insertion order. Strings stay strings at the edges; inside this code, an Email is not a String.

Difficulty: intermediate