Polymorphic type determined by side property value

[jimirocks]

Some API returns json like this:

{ "control": "type1/X", "value": { "a": "a"}}
{ "control": "type1/Y", "value": { "a": "b"}}
{ "control": "type2/X", "value": { "c": "d"}}

Ideally I would write sealed class Value, but is there a way to let kotlinx.serialization pick up the correct serializer for value based on the property control. Moreover the control property is not an object type discriminator, but different prefixes maps to different values. In Jackson once can use TypeIdResolver for this.

I tried to write some custom serializer - while serialization is just fine, the deserialization is problematic - since there is no guarantee the control property comes sooner than value so the code below doesn't work:

loop@ while (true) {
                when (val i = compositeDecoder.decodeElementIndex(descriptor)) {
                    CompositeDecoder.READ_DONE -> break@loop
                    0 -> control = compositeDecoder.decodeStringElement(descriptor, i)
                    1 -> value = compositeDecoder.decodeSerializableElement(descriptor, i, chooseSerializer(control))
                    else -> throw SerializationException("Unknown index $i")
                }
            }

Additionaly I didn't find a way how to "remember raw value" for later decoding based on control

Thanks for help