get Eta
Estimated time of request processing. A uniqueness provider that is aware of their own throughput can return an estimate how long requests will be queued before they can be processed. Notary services use this information to potentially update clients with an expected wait time in order to avoid spamming by retries when the notary gets busy.
Parameters
num States
The number of states (input + reference) in the new request, to be added to the pending count.