code: private function handleCustomer(Order $order)
      {
          $customer = $order->getCustomer();
  
          $plentyCustomer = false;
  
          if ($customer->getType() === Customer::TYPE_NORMAL) {
              $plentyCustomer = $this->findCustomer($customer->getEmail());
          }
  
          $customerParams = $this->customerRequestGenerator->generate($customer, $order);
  
          if (!$plentyCustomer) {
              $plentyCustomer = $this->client->request('POST', 'accounts/contacts', $customerParams);
          } else {
              $this->client->request('PUT', 'accounts/contacts/' . $plentyCustomer['id'], $customerParams);
          }
  
          return $plentyCustomer;
      }
docs: @param Order $order
  
  @return array|bool|mixed