Unity - Scripting API:

public static function ExecuteHierarchy(root: GameObject, eventData: EventSystems.BaseEventData, callbackFunction: EventFunction<T>): GameObject;

public static GameObject ExecuteHierarchy(GameObject root, EventSystems.BaseEventData eventData, EventFunction<T> callbackFunction);

Parameters

root	Start GameObject.
eventData	Data associated with the Executing event.
callbackFunction	Function to execute on the gameObject components.

GameObject GameObject that handled the event.

Recurse up the hierarchy calling Execute<T> until there is a GameObject that can handle the event.