Bridge/Symfony/EventListener/SaleTransformSubscriber.php
public function onPreCopy(SaleTransformEvent $event)
    {
        $source = $event->getSource();

        if ($source instanceof OrderInterface) {
            // Prevent if order is not 'new'
            if ($source->getState() !== OrderStates::STATE_NEW) {
                $event->addMessage(new ResourceMessage(
                    'ekyna_commerce.sale.message.transform_prevented',
                    ResourceMessage::TYPE_ERROR
                ));
            }
        }
    }
public function onPreCopy(SaleTransformEvent $event)
    {
        $source = $event->getSource();

        if ($source instanceof OrderInterface) {
            // Prevent if order is not 'new'
            if ($source->getState() !== OrderStates::STATE_NEW) {
                $event->addMessage(new ResourceMessage(
                    'ekyna_commerce.sale.message.transform_prevented',
                    ResourceMessage::TYPE_ERROR
                ));
            }
        }
    }
Pre copy event handler.

@param SaleTransformEvent $event