*/ private array $customers = []; public function addCustomer(Customer $customer): self { $this->customers[] = $customer; return $this; } /** * @param array $customers * @return $this */ public function setCustomers(array $customers): self { $this->customers = $customers; return $this; } /** * @return array */ public function getCustomers(): array { return $this->customers; } /** * @return array */ public function getCustomerIds(): array { return array_filter(array_values(array_unique(array_map(function (Customer $customer) { return $customer->getId(); }, $this->customers))), function ($id) { return $id !== null; }); } public function hasCustomers(): bool { return !empty($this->customers); } }