AnySerializer.kt

object AnySerializer : KSerializer<Any> {
    override val descriptor: SerialDescriptor = buildClassSerialDescriptor("Any")

    override fun serialize(encoder: Encoder, value: Any) {
        val jsonEncoder = encoder as JsonEncoder
        val jsonElement = serializeAny(value)
        jsonEncoder.encodeJsonElement(jsonElement)
    }

    private fun serializeAny(value: Any?): JsonElement = when (value) {
        is Map<*, *> -> {
            val mapContents = value.entries.associate { mapEntry ->
                mapEntry.key.toString() to serializeAny(mapEntry.value)
            }
            JsonObject(mapContents)
        }
        is List<*> -> {
            val arrayContents = value.map { listEntry -> serializeAny(listEntry) }
            JsonArray(arrayContents)
        }
        is Number -> JsonPrimitive(value)
        is Boolean -> JsonPrimitive(value)
        else -> JsonPrimitive(value.toString())
    }

    override fun deserialize(decoder: Decoder): Any {
        val jsonDecoder = decoder as JsonDecoder
        val element = jsonDecoder.decodeJsonElement()

        return deserializeJsonElement(element)
    }

    private fun deserializeJsonElement(element: JsonElement): Any = when (element) {
        is JsonObject -> {
            element.mapValues { deserializeJsonElement(it.value) }
        }
        is JsonArray -> {
            element.map { deserializeJsonElement(it) }
        }
        is JsonPrimitive -> element.toString()
    }
}

EnumIntSerializer.kt

open class EnumIntSerializer<E : Enum<E>>(
    private val key: (E) -> Int,
    private val enumCases: Array<E>
) : KSerializer<E> {
    override val descriptor = PrimitiveSerialDescriptor("EnumIntSerializer", PrimitiveKind.INT)

    override fun serialize(encoder: Encoder, value: E) {
        encoder.encodeInt(key(value))
    }

    override fun deserialize(decoder: Decoder): E {
        val key = decoder.decodeInt()
        return enumCases.first { key(it) == key }
    }
}