عرض عملي: GET شرطي مع ETags وcurl

خطوة بخطوة

1. Run the Shop API and call curl -i localhost:8080/products/1. Note the status and any ETag.
2. Add an ETag to the response with ResponseEntity.ok().eTag("\"v" + version + "\"").
3. Call again and copy the ETag value.
4. Send curl -i -H 'If-None-Match: "v1"' localhost:8080/products/1 and show 304 with no body.
5. Planned mistake: send the ETag without the quotes. The server treats it as a different value and returns 200. Fix: ETags are quoted strings; copy them exactly.
6. Update the product, repeat step 4, and show 200 with a new ETag.