Expanded class hierarchy of FTPExtension

class \Drupal\Core\FileTransfer\FileTransfer
- class \Drupal\Core\FileTransfer\FTP
  - class \Drupal\Core\FileTransfer\FTPExtension implements ChmodInterface
- class \Drupal\Core\FileTransfer\Local implements ChmodInterface
- class \Drupal\Core\FileTransfer\SSH implements ChmodInterface
- class \Drupal\system\Tests\FileTransfer\TestFileTransfer