Merge branch 'dto-serlialization' into extender-dtos

Author: JasonTheAdams

src/Common/AbstractDataValueObject.php

@@ -46,7 +46,7 @@ protected static function validateFromArrayData(array $data, array $requiredKeys
         $missingKeys = [];
 
         foreach ($requiredKeys as $key) {
-            if (!isset($data[$key])) {
+            if (!array_key_exists($key, $data)) {
                 $missingKeys[] = $key;
             }
         }