fix(webapi): Set correct swagger return type for transmission list (#…

…1590)

<!--- Provide a general summary of your changes in the Title above -->

## Description

<!--- Describe your changes in detail -->

## Related Issue(s)

- #1589 

## Verification

- [ ] **Your** code builds clean without any errors or warnings
- [ ] Manual testing done (required)
- [ ] Relevant automated test added (if you find this hard, leave it and
we'll help out)

## Documentation

- [ ] Documentation is updated (either in `docs`-directory, Altinnpedia
or a separate linked PR in
[altinn-studio-docs.](https://github.com/Altinn/altinn-studio-docs), if
applicable)

docs/schema/V1/swagger.verified.json

@@ -6747,7 +6747,10 @@
             "content": {
               "application/json": {
                 "schema": {
-                  "$ref": "#/components/schemas/V1ServiceOwnerDialogTransmissionsQueriesSearch_Transmission"
+                  "items": {
+                    "$ref": "#/components/schemas/V1ServiceOwnerDialogTransmissionsQueriesSearch_Transmission"
+                  },
+                  "type": "array"
                 }
               }
             },

src/Digdir.Domain.Dialogporten.WebApi/Endpoints/V1/ServiceOwner/DialogTransmissions/Search/SearchDialogTransmissionEndpoint.cs

@@ -22,7 +22,7 @@ public override void Configure()
         Policies(AuthorizationPolicy.ServiceProvider);
         Group<ServiceOwnerGroup>();
 
-        Description(b => b.ProducesOneOf<TransmissionDto>(
+        Description(b => b.ProducesOneOf<List<TransmissionDto>>(
             StatusCodes.Status200OK,
             StatusCodes.Status404NotFound,
             StatusCodes.Status410Gone));