Deprecation message with PHP 8.1

Problem/Motivation

There is a deprecation message with PHP 8.1 when the paypage is being set up (displayed later, after the payment is either cancelled or completed).

Deprecated function: trim(): Passing null to parameter #1 ($string) of type string is deprecated in Drupal\commerce_unzer\Utility\UnzerAddressConverter::convertAddressToUnzerData() (line 74 of modules/contrib/commerce_unzer/src/Utility/UnzerAddressConverter.php).

Drupal\commerce_unzer\Utility\UnzerAddressConverter::convertAddressToUnzerData(Object) (Line: 116)
Drupal\commerce_unzer\PluginForm\OffsiteRedirect\UnzerForm->buildConfigurationForm(Array, Object) (Line: 108)
Drupal\commerce_payment\Plugin\Commerce\InlineForm\PaymentGatewayForm->buildInlineForm(Array, Object) (Line: 218)
Drupal\commerce_payment\Plugin\Commerce\CheckoutPane\PaymentProcess->buildPaneForm(Array, Object, Array) (Line: 546)
Drupal\commerce_checkout\Plugin\Commerce\CheckoutFlow\CheckoutFlowWithPanesBase->buildForm(Array, Object, 'payment')
call_user_func_array(Array, Array) (Line: 531)
Drupal\Core\Form\FormBuilder->retrieveForm('commerce_checkout_flow_jt_multistep', Object) (Line: 278)
Drupal\Core\Form\FormBuilder->buildForm(Object, Object) (Line: 219)
Drupal\Core\Form\FormBuilder->getForm(Object, 'payment') (Line: 143)
Drupal\commerce_checkout\Controller\CheckoutController->formPage(Object)
call_user_func_array(Array, Array) (Line: 123)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 564)
Drupal\Core\Render\Renderer->executeInRenderContext(Object, Object) (Line: 124)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext(Array, Array) (Line: 97)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 158)
Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1) (Line: 80)
Symfony\Component\HttpKernel\HttpKernel->handle(Object, 1, 1) (Line: 58)
Drupal\Core\StackMiddleware\Session->handle(Object, 1, 1) (Line: 48)
Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object, 1, 1) (Line: 106)
Drupal\page_cache\StackMiddleware\PageCache->pass(Object, 1, 1) (Line: 85)
Drupal\page_cache\StackMiddleware\PageCache->handle(Object, 1, 1) (Line: 49)
Asm89\Stack\Cors->handle(Object, 1, 1) (Line: 48)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 1, 1) (Line: 38)
Drupal\webprofiler\StackMiddleware\WebprofilerMiddleware->handle(Object, 1, 1) (Line: 51)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1, 1) (Line: 23)
Stack\StackedHttpKernel->handle(Object, 1, 1) (Line: 710)
Drupal\Core\DrupalKernel->handle(Object) (Line: 19)