changeset example

$afterLineItems = $this->fetchOrderLineItems($ids);

            $changes = [];

            foreach ($beforeLineItems as $id => $lineItem) {
                $changes = [...$changes, ...$this->calculateChanges($id, $lineItem, $afterLineItems[$id] ?? null)];
            }

            foreach ($afterLineItems as $id => $lineItem) {
                // this item was added, decrease the stock                 if (!isset($beforeLineItems[$id])) {
                    $changes[] = $this->changeset($id, $lineItem['referenced_id'], 0, (int) $lineItem['quantity']);
                }
            }

            $this->stockStorage->alter($changes, $context);
        });
    }

    public function stateChanged(StateMachineTransitionEvent $event): void
    {
        if (!$this->isEnabled()) {
            return;
        }