does anyone know how to fix `Error:(33, 76) Kotlin...

# announcements

[Hexa]

does anyone know how to fix Error:(33, 76) Kotlin: Unresolved reference: messageIndex in this line here? https://gist.github.com/rinnegan/878a8451bbae54441a588e75a5acbacd#file-group-by-messageindex-L33 . I want to group by MessageIndex. Code does not work if I remove val messageIndex: MessageIndex from this class

data class MessageSender(
        val message: String

        //, val messageIndex: MessageIndex
)

[Nikky]

on first glance it looks like it in that context is some sort of list, maybe you meant to map or forEach