Support metrics for request queuing

As a service owner I'd like to know if there is a delay in receiving requests upstream from my service (e.g. firewalls, load balancers, etc).

Describe the solution you'd like
Given the presence of the header X-Request-Start or X-Queue-Start containing the timestamp of request transmission, we can calculate how long it took for our service to receive the request. This helps service owners to understand upstream delays that are not traditionally captured by examining how long it takes to process a request.

See also:

• https://docs.newrelic.com/docs/apm/applications-menu/features/request-queue-server-configuration-examples/