https://discord.com/developers/docs/resources/guild-scheduled-event#guild-scheduled-event-user-object-guild-scheduled-event-user-structure
The scheduled event id which the user subscribed to
Optional
The guild member data for this user for the guild which this event belongs to, if any
The user which subscribed to the event
See
https://discord.com/developers/docs/resources/guild-scheduled-event#guild-scheduled-event-user-object-guild-scheduled-event-user-structure