currentActivityHash property
If the user is in an activity, this will be the hash of the Activity being played. Note that you must combine this info with currentActivityModeHash to get a real picture of what the user is doing right now. For instance, PVP "Activities" are just maps: it's the ActivityMode that determines what type of PVP game they're playing.
Implementation
@JsonKey(name:'currentActivityHash')
int? currentActivityHash;