/**
* Get a default Finder object for a Drupal codebase.
*
* This method can be used two ways:
* - Override this method and provide your own default Finder object for
* copyCodebase().
* - Call the method to get a default Finder object which can then be
* modified for other purposes.
*
* @return \Symfony\Component\Finder\Finder
* A Finder object ready to iterate over core codebase.
*/