The result of MillionSend.Contacts.create_batch/3: one Item per
successful request item (in request order), per-status counts
(created/updated/skipped/failed, summing to the request length) and,
in permissive mode, the failed items as errors.
Summary
Types
@type t() :: %MillionSend.Contacts.BatchResponse{ counts: map(), data: [MillionSend.Contacts.BatchResponse.Item.t()], errors: [MillionSend.BatchError.t()] }