/**
  * Clean up abandoned fields.
  */
 public function cleanup()
 {
     $fieldTypes = app('field_type.collection')->lists('namespace');
     $this->model->leftJoin('streams_streams', 'streams_fields.namespace', '=', 'streams_streams.namespace')->whereNull('streams_streams.id')->delete();
     $this->model->where('slug', '')->delete();
     $this->model->where('namespace', '')->delete();
     $this->model->whereNotIn('type', $fieldTypes)->delete();
     $translations = $this->model->getTranslationModel();
     $translations->leftJoin('streams_fields', 'streams_fields_translations.field_id', '=', 'streams_fields.id')->whereNull('streams_fields.id')->delete();
 }