'JsonIgnoreCondition.WhenWritingNull' is not valid on value-type member

[craigktreasure]

NSwag.ApiDescription.Client: 13.16.1

Generating a client with the following OpenApiProjectReference options:

/generateClientInterfaces:true /jsonLibrary:SystemTextJson /generateOptionalParameters:true /disposeHttpClient:false /injectHttpClient:true /useBaseUrl:false /classStyle:Poco /generateJsonMethods:true

Consider the following type:

public class MyClass
{
    public Guid Id { get; set; }
}

Classes with Guid typed properties are now annotated with a [System.Text.Json.Serialization.JsonIgnore(Condition = System.Text.Json.Serialization.JsonIgnoreCondition.WhenWritingNull)] attribute, which is causing the following serialization error to be thrown when calling ToJson() on the object:

System.InvalidOperationException : The ignore condition 'JsonIgnoreCondition.WhenWritingNull' is not valid on value-type member 'Id' on type 'MyClass'. Consider using 'JsonIgnoreCondition.WhenWritingDefault'.

The issue first appeared in 13.16.0 and was last working in version 13.15.10.

[FaizulHussain]

I'm also facing similar problem :(

System.InvalidOperationException : The ignore condition 'JsonIgnoreCondition.WhenWritingNull' is not valid on value-type member '...' on type '...'. Consider using 'JsonIgnoreCondition.WhenWritingDefault'.

[sdecoodt]

This is a duplicate of #4012, there is even a PR linked there