Retry-After-Header is Missing

[Yuri-Lima]

It looks like we have a missing headers where the documents says: When you exceed the throttle threshold, the API will return a HTTP 429 status code and a Retry-After-Header indicating how many seconds you will have to wait before you can call the API again.
Related to ** Throttling**
I have tried to get by response.headers['Retry-After-Header'] and response.headers['Retry-After'] and response.headers['retry-after'] and checked all response there is nothing there.

There is an issue opened here too: https://roadmap.billbee.io/feedback/162967