/**
  * {@inheritdoc}
  */
 protected function convertNumericIdentifierToString(array $item)
 {
     $item = parent::convertNumericIdentifierToString($item);
     if (isset($item[$this->getIdentifierCode()]) && is_int($item[$this->getIdentifierCode()])) {
         $item[$this->getIdentifierCode()] = (string) $item[$this->getIdentifierCode()];
     }
     return $item;
 }
 /**
  * {@inheritdoc}
  */
 protected function getIteratorOptions()
 {
     $options = parent::getIteratorOptions();
     if ('csv' === $this->getExtension()) {
         $options['parser_options'] = ['delimiter' => $this->delimiter, 'escape' => $this->escape, 'enclosure' => $this->enclosure, 'encoding' => $this->encoding];
     }
     return $options;
 }