IndexOutOfBoundsException on Generics Subclass Serialization

Describe the bug I’m trying to create a generic class called Event that takes in a generic serializable payload and can be converted into Json. I’d prefer this so I can eventually pass the code into a function that takes in an object of type Event and serializes it for a call. Something like this:

object EventPublisher {
    private val client = HttpClient(CIO)

    suspend fun <reified T>  publish(event: Event<T>) {
        client.post("http://127.0.0.1:8080/events") {
            setBody(event)
        }
    }
}

so I can publish events of all types from my app.

To Reproduce The following is what gives the error:

@Serializable
sealed class Event<T>(
    val message: String,
    val payload: T
) {
    
    @Serializable
    data class UserCreated(
        val user: User,
    ) : Event<User>(
        "User created",
        user
    )
}

@Serializable
data class User(
    val id: String,
    val name: String
)

fun main() {
    val user = User("id", "Alice")
    println(Json.encodeToString(Event.UserCreated(user)))
}

The two following code snippets seem identical to the one above, but seem to not cause any error:

@Serializable
sealed class Event<T>(
    val message: String,
    val payload: T
) {
    @Serializable
    class UserCreated<T>(
        private val user: T
    ) : Event<T>("StringEvent", user) where T : User
}


@Serializable
data class User(
    val id: String,
    val name: String
)

fun main() {
    val user = User("id", "Alice")
    println(Json.encodeToString(Event.UserCreated(user)))
}

@Serializable
sealed class Event<T>(
    val message: String,
) {
    abstract val payload: T

    @Serializable
    data class UserCreated(
        val user: User,
    ) : Event<User>(
        "User created"
    ) {
        override val payload = user
    }
}

@Serializable
data class User(
    val id: String,
    val name: String
)

fun main() {
    val user = User("id", "Alice")
    println(Json.encodeToString(Event.UserCreated(user)))
}

Expected behavior Compile and work just like the working examples I provided.

Environment

• Kotlin version: 1.6.10
• Kotlin platforms: JVM
• Gradle version: 7.2
• Plugin: id("org.jetbrains.kotlin.plugin.serialization") version "1.6.20-M1"
• Dependencies:

implementation(platform("io.ktor:ktor-bom:2.0.0-beta-1"))
implementation("io.ktor:ktor-client-core")
implementation("io.ktor:ktor-client-content-negotiation")
implementation("io.ktor:ktor-client-serialization")
implementation("io.ktor:ktor-client-cio")

[JHarzenetter]

I’m having the same Problem

[sandwwraith]

Duplicate of #1264