@Override
  public Map<String, Object> apply(CalendarEventModel eventModel, TransformerContext context) {
    Map<String, Object> graphCalendar = new LinkedHashMap<>();

    graphCalendar.put("subject", eventModel.getTitle());

    copyDateTime("start", eventModel.getStartTime(), graphCalendar);
    copyDateTime("end", eventModel.getStartTime(), graphCalendar);
    copyLocation(eventModel, graphCalendar);
    copyBody(eventModel, graphCalendar);
    copyAttendees(eventModel, graphCalendar);

    return graphCalendar;
  }
Maps from a transfer event type to a Graph API event resource as defined by:
https://developer.microsoft.com/en-us/graph/docs/api-reference/v1.0/resources/event.
extensions/data-transfer/portability-data-transfer-microsoft/src/main/java/org/datatransferproject/transfer/microsoft/transformer/calendar/ToGraphEventTransformer.java