code: protected function renderDataCellContent($model, $key, $index)
      {
          if ($this->content !== null) {
              return parent::renderDataCellContent($model, $key, $index);
          }
  
          if ($this->radioOptions instanceof Closure) {
              $options = call_user_func($this->radioOptions, $model, $key, $index, $this);
          } else {
              $options = $this->radioOptions;
              if (!isset($options['value'])) {
                  $options['value'] = is_array($key) ? json_encode($key, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE) : $key;
              }
          }
          $checked = isset($options['checked']) ? $options['checked'] : false;
          return Html::radio($this->name, $checked, $options);
      }
docs: {@inheritdoc}