c# client : response headers invalid parsing

The header collection is wrongly populated.

For instance:

https://dev.fitbit.com/docs/explore/#/Activity/get_1_user___activities_date__date__json

is generated as:

public ApiResponse<Object> v1UserActivitiesDateDateJsonGetWithHttpInfo (string date) { ... return new ApiResponse<Object>(localVarStatusCode, localVarResponse.Headers.ToDictionary(x => x.Key, x => x.Value.ToString()), null); }

I simply replaced x.Value.ToString() with x => String.Join(",", x.Value.ToArray()) to solve the problem for now:

public ApiResponse<Object> v1UserActivitiesDateDateJsonGetWithHttpInfo (string date) { ... return new ApiResponse<Object>(localVarStatusCode, localVarResponse.Headers.ToDictionary(x => x.Key, x => String.Join(",", x.Value.ToArray())), null); }

I'm running swagger-codegen 2.2.3 on MacOSX installed with Homebrew.
To reproduce the problem, generate a csharp client api with the following command:

swagger-codegen generate -i https://dev.fitbit.com/docs/explore/fitbit-web-api.swagger.json -l csharp

Related issues : #6387 #6388

Reproduce the issue with the provided swagger-codegen command and inspect the generated C# client's response-header conversion in v1UserActivitiesDateDateJsonGetWithHttpInfo. Confirm that headers with multiple values are preserved rather than collapsed by ToString(), then verify the generated client handles the Fitbit API response correctly.