PluginExample.php

<?php

namespace Drupal\plugin_test\Plugin\Annotation;

use Drupal\Component\Annotation\AnnotationBase;

/**
 * Defines a custom Plugin annotation.
 *
 * @Annotation
 */
class PluginExample extends AnnotationBase {
    
    /**
     * The plugin ID.
     *
     * @var string
     */
    public $id;
    
    /**
     * Another plugin metadata.
     *
     * @var string
     */
    public $custom;
    
    /**
     * {@inheritdoc}
     */
    public function get() {
        return [
            'id' => $this->id,
            'custom' => $this->custom,
            'class' => $this->class,
            'provider' => $this->provider,
        ];
    }

}