No idempotency support on POST requests #197
Description
POST requests do not have Idempotent-Key or similar mechanisms to ensure safe retries. While returning the response, HTTP requests are stateless, and care returns are with broken pipes and Socket exceptions. Subsequent requests to POST (e.g. create an account) will result in a duplicate account.
Expected behaviour:
- Introduce the Idempotent-Key header to enable callers to identify the request uniquely
- Once the same Idempotent-Key is received subsequently, produce exactly the same response as for the first request.