Currently none of the rate limiting headers are available to a rest client.

Have roundup return an 'Access-Control-Expose-Headers' header with at least the following 
value:

X-RateLimit-Limit, X-RateLimit-Remaining, X-RateLimit-Reset, X-RateLimit-Limit-Period, Retry-
After, Allow, Sunset

This includes all the rate limit headers to throttle requests.
The allow header so it can determine how to query the endpoint.
The sunset header so it can see if it's using a deprecated API endpoint.

Ref: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Access-Control-Expose-Headers