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I’m following along with <https://github.com/Kotlin/kotlinx.serialization/blob/master/docs/polymorphism.md#objects> and I found that the list of multiple objects caused the type to show up, but if I only had EmptyResponse, then the output would just be [{}]. Is there a way to force it to give the type when there’s only one object?

A list of two EmptyResponse gave [{}, {}], but if I made a second object and used both, it would give the types.

Code snippet? I'm 99.99% sure I know what's wrong.

yep. symptom sounds you're calling the serializer with the wrong reified type.

I’m calling `Json.encodeToString(listOf(EmptyResponse, EmptyResponse))` . This is currently only for encoding. I’m not decoding it yet.

`Json.encodeToString(listOf&lt;BaseClass&gt;(EmptyResponse, EmptyResponse))`

Same result with `Json.encodeToString(EmptyResponse)`

`Json.encodeToString&lt;BaseClass&gt;(EmptyResponse)`

also
```val list: List&lt;BaseClass&gt; = listOf(EmptyResponse)
Json.encodeToString(list)```
and all sorts of other variations

Interesting. Why does it require that I explicitly mark it as Response?

because Kotlin infers the narrowest possible type for `listOf(EmptyResponse)` unless it has another reason to, which is `List&lt;EmptyResponse&gt;`, which is not polymorphic

I would tend to avoid the reified helper functions in kotlinx.serialization anyway, due to the need for reflection to obtain the serializer (waiting on <https://github.com/Kotlin/kotlinx.serialization/issues/1348>)

That makes sense. I guess I’ll have to be careful when I work with polymorphic serializers. I noticed that even when I used a serializerModule, it would still happen. I would have assumed that the fact that I marked EmptyClass as a subclass would tell it to use polymorphism.

no, EmptyClass is only polymorphic in the context of a BaseClass

you can register a class as belonging to multiple polymorphic hierarchies