get_sortable_columns() public method

Return the sortable columns
public get_sortable_columns ( ) : array
return array
 /**
  * Return the sortable columns
  *
  * @brief Sortable columns
  *
  * @return array
  */
 public function get_sortable_columns()
 {
     // Ask to the the model
     if (isset($this->model) && method_exists($this->model, 'get_sortable_columns')) {
         return $this->model->get_sortable_columns();
     }
     return array();
 }