The new current ChannelState.
Optional
hasIndicates whether the client can expect a backlog of messages from a rewind or resume.
The previous state. For the ChannelEvents.UPDATE event, this is equal to the current
ChannelState.
Optional
reasonAn ErrorInfo object containing any information relating to the transition.
Indicates whether message continuity on this channel is preserved, see Nonfatal channel errors for more info.
Contains state change information emitted by Channel and RealtimeChannel objects.