TipsPluginCollection.php

<?php

namespace Drupal\tour;

use Drupal\Core\Plugin\DefaultLazyPluginCollection;

/**
 * A collection of tips.
 */
class TipsPluginCollection extends DefaultLazyPluginCollection {
    
    /**
     * {@inheritdoc}
     */
    protected $pluginKey = 'plugin';
    
    /**
     * {@inheritdoc}
     *
     * @return \Drupal\tour\TipPluginInterface
     */
    public function &get($instance_id) {
        return parent::get($instance_id);
    }

}