/**
  * Validate theme data
  *
  * @return $this
  * @throws \Magento\Framework\Exception\LocalizedException
  */
 protected function _validate()
 {
     if (!$this->_validator->validate($this)) {
         $messages = $this->_validator->getErrorMessages();
         throw new \Magento\Framework\Exception\LocalizedException(__(implode(PHP_EOL, reset($messages))));
     }
     return $this;
 }