Description

When generating a csharp client the "Accept" header is set differently for the sync and async version of the API. In our case this leads to the api using "application/xml" for the async variant and "application/json" for the sync variant.
I suspect the main reason for this is that the lines

var localVarAccept = {{packageName}}.Client.ClientUtils.SelectHeaderAccept(_accepts);
if (localVarAccept != null) localVarRequestOptions.HeaderParameters.Add("Accept", localVarAccept);

are not used for the async template.
This only happens if "application/xml" occurs later than "application/json" in the array of supported_accept media types.

openapi-generator version

4.3.1

OpenAPI declaration file content or url

https://gist.github.com/mh03r932/8d2e7c390169e3cec49b62928e0f102a

Command line used for generation

Client was generated using the maven plugin with the following config

<configOptions>
    <packageName>FeWoFeondi.RestApiClient</packageName>
    <targetFramework>netstandard2.1</targetFramework>
    <netCoreProjectFile>true</netCoreProjectFile>
    <optionalEmitDefaultValues>true</optionalEmitDefaultValues>
    <releaseNote>This Code was generated using OpenApiTools https://github.com/OpenAPITools/</releaseNote>
    <optionalAssemblyInfo>false</optionalAssemblyInfo>
</configOptions>

Steps to reproduce

• Generate any client that supports application/xml and application/json as accept mediatypes
• make sure the "application/xml" media type is last entry in the _accepts String array in the generated api-class you are testing.
• check the sent headers dependeing on wether the async or the sync variant is used

Suggest a fix

Add the following two lines after Line 426 in api.mustache
var localVarAccept = {{packageName}}.Client.ClientUtils.SelectHeaderAccept(_accepts); if (localVarAccept != null) localVarRequestOptions.HeaderParameters.Add("Accept", localVarAccept);

Basic pull-request #mh03r932#1