AutoRest生成C#模型时multipart/form-data含字符串枚举报错

我尝试通过OpenAPI规范YAML文件生成C#模型与客户端，当multipart/form-data类型的请求体包含如下字符串枚举类型的Precedence属性时：

requestBody:
  required: true
  content:
    multipart/form-data:
      schema:
        type: object
        properties:
          Precedence:
            type: string
            enum:
              - PRIMARY
              - SECONDARY
              - COMMON

执行生成命令会抛出System.NotImplementedException错误，完整错误栈如下：

fatal   | System.NotImplementedException: The method or operation is not implemented.
   at AutoRest.CSharp.Output.Models.RestClientBuilder.BuildRequestBody(IReadOnlyCollection`1 allParameters, BodyMediaType bodyMediaType, OutputLibrary library) in D:\a\_work\1\s\autorest.csharp\src\AutoRest.CSharp\Common\Output\Models\RestClientBuilder.cs:line 285
   at AutoRest.CSharp.Output.Models.RestClientBuilder.BuildRequest(InputOperation operation, IReadOnlyCollection`1 requestParts, Parameter bodyParameter, OutputLibrary library) in D:\a\_work\1\s\autorest.csharp\src\AutoRest.CSharp\Common\Output\Models\RestClientBuilder.cs:line 212
   at AutoRest.CSharp.Output.Models.RestClientBuilder.BuildMethod(InputOperation operation, DataPlaneResponseHeaderGroupType responseHeaderModel) in D:\a\_work\1\s\autorest.csharp\src\AutoRest.CSharp\Common\Output\Models\RestClientBuilder.cs:line 113    
   at AutoRest.CSharp.Output.Models.DataPlaneRestClient.EnsureNormalMethods() in D:\a\_work\1\s\autorest.csharp\src\AutoRest.CSharp\DataPlane\Output\DataPlaneRestClient.cs:line 44
   at System.Lazy`1.ViaFactory(LazyThreadSafetyMode mode)
   at System.Lazy`1.ExecutionAndPublication(LazyHelper executionAndPublication, Boolean useDefaultConstructor)
   at System.Lazy`1.CreateValue()
   at AutoRest.CSharp.Output.Models.RestClient.GetOperationMethod(InputOperation request) in D:\a\_work\1\s\autorest.csharp\src\AutoRest.CSharp\Common\Output\Models\RestClient.cs:line 107
   at AutoRest.CSharp.Output.Models.RestClient.BuildAllMethods()+MoveNext() in D:\a\_work\1\s\autorest.csharp\src\AutoRest.CSharp\Common\Output\Models\RestClient.cs:line 45
   at System.Collections.Generic.LargeArrayBuilder1.AddRange(IEnumerable1 items)
   at System.Collections.Generic.EnumerableHelpers.ToArray[T](IEnumerable`1 source)
   at AutoRest.CSharp.Output.Models.RestClient.getMethods() in D:\a\work\1\s\autorest.csharp\src\AutoRest.CSharp\Common\Output\Models\RestClient.cs:line 24
   at AutoRest.CSharp.Generation.Writers.RestClientWriter.WriteClient(CodeWriter writer, DataPlaneRestClient restClient) in D:\a\_work\1\s\autorest.csharp\src\AutoRest.CSharp\Common\Generation\Writers\RestClientWriter.cs:line 32
   at AutoRest.CSharp.AutoRest.Plugins.DataPlaneTarget.Execute(GeneratedCodeWorkspace project, CodeModel codeModel, SourceInputModel sourceInputModel, SchemaUsageProvider schemaUsageProvider) in D:\a\_work\1\s\autorest.csharp\src\AutoRest.CSharp\DataPlane\AutoRest\DataPlaneTarget.cs:line 55
   at AutoRest.CSharp.AutoRest.Plugins.CSharpGen.ExecuteAsync(CodeModel codeModel) in D:\a\_work\1\s\autorest.csharp\src\AutoRest.CSharp\Common\AutoRest\Plugins\CSharpGen.cs:line 38
   at AutoRest.CSharp.AutoRest.Plugins.CSharpGen.Execute(IPluginCommunication autoRest) in D:\a\_work\1\s\autorest.csharp\src\AutoRest.CSharp\Common\AutoRest\Plugins\CSharpGen.cs:line 128
   at AutoRest.CSharp.AutoRest.Plugins.PluginProcessor.Start(IPluginCommunication autoRest) in D:\a\_work\1\s\autorest.csharp\src\AutoRest.CSharp\Common\AutoRest\Plugins\PluginProcessor.cs:line 39
fatal   | Process() cancelled due to failure 

使用的生成命令：
autorest --input-file=swagger.yaml --csharp --generation1-convenience-client

移除枚举定义后，生成可正常执行。

临时解决方案 #

• 先移除YAML中的枚举定义，将Precedence改为普通字符串类型，生成代码后再手动将该字段替换为对应的C#枚举类型
• 将Precedence枚举字段从multipart/form-data请求体中提取为URL查询参数，避免在表单数据中使用枚举类型

内容的提问来源于stack exchange，提问作者Akash Rawat