Can a reservation check in?

Reservation.cs

public virtual CheckInRequestResult CanCheckIn(EventHydrationContext ehc, IClock clock,
    ReservationFolioState fs) {
  if (State == ReservationState.CheckedIn) {
    return CheckInRequestResult.AlreadyCheckedIn;
  }
  
  if (State != ReservationState.Open) {
    return CheckInRequestResult.NoOpenReservation;
  }

  if (!IsAllowableCheckinTime(clock)) {
    return CheckInRequestResult.TooEarlyToCheckin;
  }