Bug: ObsoleteAttribute is not applied to classes that have a base class.

[SebastianStehle]

I have a class with a base class in C# and the following schema is generated in my API:

{
   "WebhookRuleActionDto":{
      "allOf":[
         {
            "$ref":"#/components/schemas/RuleActionDto"
         },
         {
            "type":"object",
            "deprecated":true,
            "x-deprecatedMessage":"Has been replaced by flows.",
            "additionalProperties":false,
            "required":[
               "url",
               "method"
            ],
            "properties":{
               
            }
         }
      ]
   }
}

(I have simplified it a little bit).

By default the class has no Obsolete attribute because the model only checks at the root schema:

NJsonSchema/src/NJsonSchema.CodeGeneration.CSharp/Models/ClassTemplateModel.cs

Line 178 in f68e664

public bool IsDeprecated => _schema.IsDeprecated;

I solved it with a little bit of postprocessing, but I think it should just work.

public static void AddDeprecations(OpenApiDocument document)
{
    foreach (var (name, scheme) in document.Components.Schemas)
    {
        if (scheme.IsDeprecated)
        {
            continue;
        }

        if (scheme.AllOf != null && scheme.AllOf.Count > 0)
        {
            foreach (var allOf in scheme.AllOf)
            {
                if (!string.IsNullOrWhiteSpace(allOf.DeprecatedMessage))
                {
                    Console.WriteLine($"Add Deprecation to: {name}");
                    scheme.DeprecatedMessage = allOf.DeprecatedMessage;
                    scheme.IsDeprecated = true;
                    break;
                }
            }
        }
    }
}