trait SelectionTrait in Drupal 8

trait SelectionTrait {

  /**
   * The entity manager service.
   *
   * @var \Drupal\Core\Entity\EntityManagerInterface
   */
  protected $entityManager;

  /**
   * The module handler service.
   *
   * @var \Drupal\Core\Extension\ModuleHandlerInterface
   */
  protected $moduleHandler;

  /**
   * The current user.
   *
   * @var \Drupal\Core\Session\AccountInterface
   */
  protected $currentUser;

  /**
   * Constructs a new selection object.
   *
   * @param array $configuration
   *   A configuration array containing information about the plugin instance.
   * @param string $plugin_id
   *   The plugin_id for the plugin instance.
   * @param mixed $plugin_definition
   *   The plugin implementation definition.
   * @param \Drupal\Core\Entity\EntityManagerInterface $entity_manager
   *   The entity manager service.
   * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
   *   The module handler service.
   * @param \Drupal\Core\Session\AccountInterface $current_user
   *   The current user.
   */
  public function __construct(array $configuration, $plugin_id, $plugin_definition, EntityManagerInterface $entity_manager, ModuleHandlerInterface $module_handler, AccountInterface $current_user) {
    parent::__construct($configuration, $plugin_id, $plugin_definition);
    $this->entityManager = $entity_manager;
    $this->moduleHandler = $module_handler;
    $this->currentUser = $current_user;
  }

  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
    return new static($configuration, $plugin_id, $plugin_definition, $container
      ->get('entity.manager'), $container
      ->get('module_handler'), $container
      ->get('current_user'));
  }

}