class ActionAdminManageForm

class ActionAdminManageForm extends FormBase {
    
    /**
     * The action plugin manager.
     *
     * @var \Drupal\Core\Action\ActionManager
     */
    protected $manager;
    
    /**
     * Constructs a new ActionAdminManageForm.
     *
     * @param \Drupal\Core\Action\ActionManager $manager
     *   The action plugin manager.
     */
    public function __construct(ActionManager $manager) {
        $this->manager = $manager;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container) {
        return new static($container->get('plugin.manager.action'));
    }
    
    /**
     * {@inheritdoc}
     */
    public function getFormId() {
        return 'action_admin_manage';
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildForm(array $form, FormStateInterface $form_state) {
        $actions = [];
        foreach ($this->manager
            ->getDefinitions() as $id => $definition) {
            if (is_subclass_of($definition['class'], '\\Drupal\\Core\\Plugin\\PluginFormInterface')) {
                $actions[$id] = $definition['label'];
            }
        }
        asort($actions);
        $form['parent'] = [
            '#type' => 'details',
            '#title' => $this->t('Create an advanced action'),
            '#attributes' => [
                'class' => [
                    'container-inline',
                ],
            ],
            '#open' => TRUE,
        ];
        $form['parent']['action'] = [
            '#type' => 'select',
            '#title' => $this->t('Action'),
            '#title_display' => 'invisible',
            '#options' => $actions,
            '#empty_option' => $this->t('- Select -'),
        ];
        $form['parent']['actions'] = [
            '#type' => 'actions',
        ];
        $form['parent']['actions']['submit'] = [
            '#type' => 'submit',
            '#value' => $this->t('Create'),
        ];
        return $form;
    }
    
    /**
     * {@inheritdoc}
     */
    public function submitForm(array &$form, FormStateInterface $form_state) {
        if ($form_state->getValue('action')) {
            $form_state->setRedirect('action.admin_add', [
                'action_id' => $form_state->getValue('action'),
            ]);
        }
    }

}