[BUG][csharp-netcore] Failed to deserialize FileParameter when using HttpClient.

Created by: TORISOUP

Description

When a client that returns byte[] (FileParameter) as a response is created and called, FileParameter is interpreted as Json and decoded, resulting in an exception.

openapi-generator version

5.2.1.

Related issues/PRs

I'm sorry if this has already been pointed out.

Suggest a fix/enhancement

In the next conditional branch, it looks like the fact that FileParameter is passed is not taken into account.

https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/main/resources/csharp-netcore/libraries/httpclient/ApiClient.mustache#L99-L147

For now, by adding the following code, I was able to get the byte[] without any error.

if (type == typeof(FileParameter))
{
    return new FileParameter(await response.Content.ReadAsStreamAsync());
}