JobsListAdapter2.kt

class JobsListAdapter : ListAdapter<JobListItem, JobViewHolder>() {

    override fun getItemViewType(position: Int): Int {
        return getItem(position).ordinal()
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): JobViewHolder {
        return when (viewType) {
            Header.ordinal() -> HeaderViewHolder(...)
            JobItem.ordinal() -> JobViewHolder(...)
            else -> throw IllegalStateException()
        }
    }
}

sealed class JobListItem {

    object Header : JobListItem()

    data class JobItem(val payload: Payload) : JobListItem(){
        companion object
    }

}

inline fun <reified T : Any> T.ordinal(): Int {
    if (T::class.isSealed) {
        return T::class.java.classes.indexOfFirst { sub -> sub == javaClass }
    }

    val klass = if (T::class.isCompanion) {
        javaClass.declaringClass
    } else {
        javaClass
    }

    return klass.superclass?.classes?.indexOfFirst { it == klass } ?: -1
}