How to get remote post handler returned response at module file?

Question

I want to get remote post handler returned response inside hook_webform_handler_invoke_post_save_alter.

Please help me.

function hook_webform_handler_invoke_post_save_alter(\Drupal\webform\Plugin\WebformHandlerInterface $handler, array &$args) {
 $webform = $handler->getWebform();
 $webform_submission = $handler->getWebformSubmission();
 $webform_id = $webform->id();
 $handler_id = $handler->getHandlerId();
 if ($webform_id == 'webform_id' && $handler_id == 'handler_id') {
  // how to get here remote post returned response ??
 }

}