ChannelTruncatedEvent
data class ChannelTruncatedEvent(val type: String, val createdAt: Date, val rawCreatedAt: String, val cid: String, val channelType: String, val channelId: String, val channel: Channel, val channelLastMessageAt: Date?, val user: User?, val message: Message?) : CidEvent, HasChannel
Triggered when a channels' history is truncated. Could contain system message.