Assign default values to billing address fields

Gateway/Request/AddressDataBuilder.php

@@ -62,15 +62,33 @@ class AddressDataBuilder implements BuilderInterface
         $billingAddress = $order->getBillingAddress();
         if ($billingAddress) {
 
-            // filter housenumber from streetLine1
-            $requestBilling = ["street" => $billingAddress->getStreetLine1(),
-                "postalCode" => $billingAddress->getPostcode(),
-                "city" => $billingAddress->getCity(),
+            $requestBilling = ["street" => "N/A",
+                "postalCode" => '',
+                "city" => "N/A",
                 "houseNumberOrName" => '',
-                "stateOrProvince" => $billingAddress->getRegionCode(),
-                "country" => $billingAddress->getCountryId()
+                "stateOrProvince" => '',
+                "country" => "ZZ"
             ];
 
+            if ($billingAddress->getStreetLine1()) {
+                $requestBilling["street"] = $billingAddress->getStreetLine1();
+            }
+
+            if ($billingAddress->getPostcode()) {
+                $requestBilling["postalCode"] = $billingAddress->getPostcode();
+            }
+
+            if ($billingAddress->getCity()) {
+                $requestBilling["city"] = $billingAddress->getCity();
+            }
+
+            if ($billingAddress->getRegionCode()) {
+                $requestBilling["stateOrProvince"] = $billingAddress->getRegionCode();
+            }
+
+            if ($billingAddress->getCountryId()) {
+                $requestBilling["country"] = $billingAddress->getCountryId();
+            }
 
             $result['billingAddress'] = $requestBilling;
         }