عرض عملي: تغيير OrderPlaced دون كسر المستهلكين

خطوة بخطوة

1. Show current Avro schema v1 and the registry set to BACKWARD_TRANSITIVE (or FULL).
2. Add money with a default and keep total; register v2; the check passes.
3. Deploy the producer to emit both fields; consumers on v1 keep working.
4. Planned mistake: remove total in the same change; the registry rejects it (or a contract test fails). Fix: keep it for a release.
5. Migrate consumers to money; watch usage of total fall to zero.
6. Register v3 removing total after the deprecation window.