public function beforeMarshal(Event $event, ArrayObject $data, ArrayObject $options)
    {
        $validator = $this->_table->getValidator();
        $dataArray = $data->getArrayCopy();
        foreach (array_keys($this->getConfig(null, [])) as $field) {
            if (!$validator->isEmptyAllowed($field, false)) {
                continue;
            }
            if (Hash::get($dataArray, $field . '.error') !== UPLOAD_ERR_NO_FILE) {
                continue;
            }
            unset($data[$field]);
        }
    }