I can successfully import and render multiple public calendars into a FullCalendar 5 instance. However, searching through returned Events as I click on each, I cannot find anything in the returned Event that identifies which Google Calendar a particular event belongs to.

I have tried adding additional information to the event source data like the "source" field, and the added fields (source, className) do show up along with BOTH Google Calendar sources at 'event._context.options.eventSources' in the returned event, but I have not found a field that indicates WHICH source is responsible for the event.

var calendar = new FullCalendar.Calendar(calendarEl, {
  googleCalendarApiKey: 'MY API KEY',
  ...
  eventSources: [
    {
      googleCalendarId: 'abcd1234@group.calendar.google.com'
      source: 'norm',
      className: 'norm'
    },
    {
      googleCalendarId: 'efgh5678@group.calendar.google.com',
      source: 'bunnie',
      className: 'bunnie'
    }
  ]

Any insight - including "Norm, you actually did not see this field?" would help.