code: public function executeAction($name, array $data = [])
      {
          if (false !== strpos($name, '.')) {
              list($name, $childKey) = explode('.', $name, 2);
              $container = $this->getForm($name);
              
              // execute child container's action
              return $container->executeAction($childKey, $data);
          }
          
          // this container defines no actions
          return [];
      }
docs: Execute an arbitrary action
  
  @param string $name Name of an action
  @param array $data Arbitrary data
  @return array