code: public function generate()
      {
          $this->type = 'dropDownList';
          $baseOptions = [];
          if (!$this->modelField->taxonomy->required) {
              $baseOptions[''] = '';
          }
          $this->options = array_merge($baseOptions, ArrayHelper::map($this->modelField->taxonomy->taxonomies, 'id', 'name'));
  
          if ($this->modelField->taxonomy->multiple) {
              $this->htmlOptions['multiple'] = true;
          }
  
          return parent::generate();
      }
docs: {@inheritdocs}.