setValue

operator fun <S> GroupState<S>.setValue( thisRef: Any?, property: KProperty<*>, value: S?)

(Kotlin-specific) Allows the group state object to be used as a delegate. Will be null if it does not exist.

For example:

groupedDataset.mapGroupsWithState(GroupStateTimeout.NoTimeout()) { key, values, state: GroupState<Int> ->
    var s by state
    ...
}