ActionManager.php

<?php

namespace Drupal\Core\Action;

use Drupal\Component\Plugin\CategorizingPluginManagerInterface;
use Drupal\Core\Cache\CacheBackendInterface;
use Drupal\Core\Extension\ModuleHandlerInterface;
use Drupal\Core\Plugin\CategorizingPluginManagerTrait;
use Drupal\Core\Plugin\DefaultPluginManager;

/**
 * Provides an Action plugin manager.
 *
 * @see \Drupal\Core\Annotation\Action
 * @see \Drupal\Core\Action\ActionInterface
 * @see \Drupal\Core\Action\ActionBase
 * @see plugin_api
 */
class ActionManager extends DefaultPluginManager implements CategorizingPluginManagerInterface {
    use CategorizingPluginManagerTrait;
    
    /**
     * Constructs a new class instance.
     *
     * @param \Traversable $namespaces
     *   An object that implements \Traversable which contains the root paths
     *   keyed by the corresponding namespace to look for plugin implementations.
     * @param \Drupal\Core\Cache\CacheBackendInterface $cache_backend
     *   Cache backend instance to use.
     * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
     *   The module handler to invoke the alter hook with.
     */
    public function __construct(\Traversable $namespaces, CacheBackendInterface $cache_backend, ModuleHandlerInterface $module_handler) {
        parent::__construct('Plugin/Action', $namespaces, $module_handler, 'Drupal\\Core\\Action\\ActionInterface', 'Drupal\\Core\\Annotation\\Action');
        $this->alterInfo('action_info');
        $this->setCacheBackend($cache_backend, 'action_info');
    }
    
    /**
     * Gets the plugin definitions for this entity type.
     *
     * @param string $type
     *   The entity type name.
     *
     * @return array
     *   An array of plugin definitions for this entity type.
     */
    public function getDefinitionsByType($type) {
        return array_filter($this->getDefinitions(), function ($definition) use ($type) {
            return $definition['type'] === $type;
        });
    }

}