name: FSPIOP-Source
in: header
schema:
  type: string
required: true
description: >-
  The `FSPIOP-Source` header field is a non-HTTP standard field used by the API
  for identifying the sender of the HTTP request. The field should be set by the
  original sender of the request. Required for routing and signature
  verification (see header field `FSPIOP-Signature`).