EventType
EventType: "participantsAddedToGroupThreadEvent" | "participantLeftGroupThreadEvent" | "threadNameEvent" | "addThreadAdminsEvent" | "planCreateEvent" | "planUpdateTitleEvent" | "planUpdateTimeEvent" | "planUpdateLocationEvent" | "planRsvpEvent" | "planDeleteEvent" | "pollCreateEvent" | "pollUpdateVoteEvent" | "changeThreadNicknameEvent" | "changeThreadIconEvent" | "changeThreadThemeEvent" | "deliveryReceiptEvent" | "readReceiptEvent"