Dropbutton.php

<?php

namespace Drupal\views\Plugin\views\field;

use Drupal\views\ResultRow;

/**
 * Provides a handler that renders links as dropbutton.
 *
 * @ingroup views_field_handlers
 *
 * @ViewsField("dropbutton")
 */
class Dropbutton extends Links {
    
    /**
     * {@inheritdoc}
     */
    public function render(ResultRow $values) {
        $links = $this->getLinks();
        if (!empty($links)) {
            return [
                '#type' => 'dropbutton',
                '#links' => $links,
            ];
        }
        else {
            return '';
        }
    }

}