Feil content for error response til /broker/api/v1/filetransfer/{fileTransferId}/download i Swagger

[esseb]

Description of the bug

/broker/api/v1/filetransfer/{fileTransferId}/download i https://docs.altinn.studio/swagger/altinn-broker-v1.json har content: application/octet-stream for alle error-responser. De burde være application/json

Steps To Reproduce

Ikke relevant.

Additional Information

No response

[coderabbitai]

A summary of the changes CodeRabbit can apply:

• Update src/Altinn.Broker.API/Controllers/FileTransferController.cs to add using Microsoft.AspNetCore.Mvc.Infrastructure, change the controller's [Produces] to ("application/octet-stream","application/json"), and annotate each [ProducesResponseType] with the correct content type (200 → application/octet-stream, 400/401/403/404 → application/json) so Swagger/OpenAPI documents binary success and JSON error responses correctly.

• Update src/Altinn.Broker.API/Controllers/FileTransferController.cs by adding the using for Microsoft.AspNetCore.Mvc.Infrastructure and replacing the existing [Produces]/[ProducesResponseType] attributes on the DownloadFile action to declare both "application/octet-stream" and "application/json" media types and to specify FileStreamResult for 200 and ProblemDetails for 400/401/403/404 responses (each with explicit status and media type).

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