* Usually setting this is not necessary as $process typically starts with
* a 'get'. This is useful only when the $process contains a single
* destination and needs to access a value outside of the source. See
- * \Drupal\migrate\Plugin\migrate\process\Iterator::transformKey for an
+ * \Drupal\migrate\Plugin\migrate\process\SubProcess::transformKey for an
* example.
*
* @throws \Drupal\migrate\MigrateException