protected function _dataToSerialize($serialize, $additionalData = []) {
		if ($serialize === true) {
			$data = array_diff_key(
				$this->viewVars,
				array_flip($this->_specialVars)
			);
			return $data;
		}

		foreach ((array)$serialize as $alias => $key) {
			if (is_numeric($alias)) {
				$alias = $key;
			}
			if (array_key_exists($key, $this->viewVars)) {
				$additionalData[$alias] = $this->viewVars[$key];
			}
		}
		return $additionalData;
	}