code: protected function buildCustomerData(Common\SaleInterface $sale)
      {
          if (null !== $customer = $sale->getCustomer()) {
              return [
                  'number'    => $customer->getNumber(),
                  'company'   => $customer->getCompany(),
                  'full_name' => trim($customer->getFirstName() . ' ' . $customer->getLastName()),
                  'email'     => $customer->getEmail(),
                  'phone'     => $this->formatPhoneNumber($customer->getPhone()),
                  'mobile'    => $this->formatPhoneNumber($customer->getMobile()),
              ];
          } else {
              return [
                  'number'    => null,
                  'company'   => $sale->getCompany(),
                  'full_name' => trim($sale->getFirstName() . ' ' . $sale->getLastName()),
                  'email'     => $sale->getEmail(),
                  'phone'     => null,
                  'mobile'    => null,
              ];
          }
      }
docs: Builds the document's customer data.
  
  @param Common\SaleInterface $sale
  
  @return array