/**
  * Returns validated and sanitized form data.
  *
  * @param array|string $data
  *
  * @return array|string
  */
 function parse_migration_form_data($data)
 {
     $form_data = parent::parse_migration_form_data($data);
     $form_data = array_intersect_key($form_data, array_flip($this->accepted_fields));
     return $form_data;
 }