A requester is a contract that makes Airnode requests. While making a request,
the requester refers to a sponsor by its
sponsorAddress, which means "fulfill my request
with the sponsor wallet of the sponsor identified by
sponsorAddress. Doing so requires the requester to be sponsored
by the said sponsor.
Note that the requester is the contract that makes the request. The requester may specify the request such that the request is fulfilled by the Airnode calling back another contract.