Multiple async file annotation requests are batched into a
single service call.
Optional. Target project and location to make a call. Format:
projects/{project-id}/locations/{location-id}. If no
parent is specified, a region will be chosen automatically.
Supported location-ids: us: USA country only, asia:
East asia areas, like Japan, Taiwan, eu: The European
Union. Example: projects/project-A/locations/eu.
