re-add missing function

Modules/Application/Model/D3ManufacturerLongDesc.php

@@ -49,4 +49,13 @@ class D3ManufacturerLongDesc extends D3ManufacturerLongDesc_parent
         $longName = $this->_getFieldLongName(Constants::D3_OXMANUFACTURERS_LONGDESC_FIELDNAME);
         return $this->$longName ?: oxNew(Field::class);
     }
+
+    /**
+     * @return string
+     */
+    public function getD3LongDescTableColumnName(): string
+    {
+        return $this->getViewName(true).'__'.Constants::D3_OXMANUFACTURERS_LONGDESC_FIELDNAME;
+    }
+
 }