private function moveFieldData(CalendarEvent $event) {
        if ($event->Attendees()->exists()) {
            /** @var Attendee $attendee */
            foreach ($event->Attendees() as $attendee) {
                /** @var UserField $field */
                foreach ($event->Fields() as $field) {
                    $q = SQLSelect::create(
                        $field->FieldName,
                        "`{$attendee->getClassName()}`",
                        array('ID' => $attendee->ID)
                    );

                    try {
                        $value = $q->execute()->value();
                        $attendee->Fields()->add($field, array(
                            'Value' => $value
                        ));
                        echo "[$event->ID][$attendee->ID] Set '$field->FieldName' with '{$value}' \n";
                    } catch (\Exception $e) {
                        // fails silent
                        echo "[$event->ID][$attendee->ID] Failed, '$field->FieldName' does not exist \n";
                    }
                }
            }
            echo "[$event->ID] Finished migrating event \n\n";
        } else {
            echo "[$event->ID] No attendees to migrate \n\n";
        }
    }