code: private function convertFileInformation($file)
      {
          if ($file instanceof FileUpload) {
              return $file;
          }
  
          $file = $this->fixPhpFilesArray($file);
          if (is_array($file)) {
              $keys = array_keys($file);
              sort($keys);
  
              if ($keys == ['error', 'name', 'size', 'tmp_name', 'type']) {
                  if (UPLOAD_ERR_NO_FILE == $file['error']) {
                      $file = null;
                  } else {
                      $file = new FileUpload($file['tmp_name'], $file['name'], $file['size'], $file['type'], $file['error']);
                  }
              } else {
                  $file = array_map([$this, 'convertFileInformation'], $file);
              }
          }
  
          return $file;
      }
docs: Converts uploaded files to FileUpload instances.
  
  @param array|FileUpload $file A (multi-dimensional) array of uploaded file information
  @return array A (multi-dimensional) array of FileUpload instances