Render the display in this style.
function render() {
if ($this
->usesRowPlugin() && empty($this->row_plugin)) {
debug('Drupal\\views\\Plugin\\views\\style\\StylePluginBase: Missing row plugin');
return;
}
// Group the rows according to the grouping instructions, if specified.
$sets = $this
->render_grouping($this->view->result, $this->options['grouping'], TRUE);
return $this
->render_grouping_sets($sets);
}