ACP2E-3486: Default values are not set for date and time attributes with products RestAPI

Author: o-iegorov

app/code/Magento/Eav/Model/Entity/Attribute/Backend/Datetime.php

@@ -50,13 +50,20 @@ public function beforeSave($object)
             }
 
             if ($value === null) {
-                $value = $object->getData($attributeName);
+                //$value = $object->getData($attributeName);
+                $value = $this->getDefaultValue();
             }
 
             $object->setData($attributeName, $value);
             $object->setData($attributeName . '_is_formated', true);
         }
 
+        $defaultValue = $this->getDefaultValue();
+        if (is_null($object->getData($attributeName)) && $defaultValue !== null) {
+            $object->setData($attributeName, $defaultValue);
+            $object->setData($attributeName . '_is_formated', true);
+        }
+
         return $this;
     }