Overrides Drupal\views\Plugin\views\field\FieldPluginBase::init().
This method assumes the taxonomy_term_data table. If using another table, we'll need to be more specific.
Overrides FieldPluginBase::init
public function init(ViewExecutable $view, &$options) {
parent::init($view, $options);
$this->additional_fields['vid'] = 'vid';
$this->additional_fields['tid'] = 'tid';
$this->additional_fields['vocabulary_machine_name'] = array(
'table' => 'taxonomy_vocabulary',
'field' => 'machine_name',
);
}