hello, who knows how get the list of all ItemContainer ?
UnityEngine.Object.FindObjectsOfType is't working

Unfortunately, you cannot find 100% all ItemContainers

UnityEngine.Object.FindObjectsOfType is't working

Because it works only for Unity objects (gameobjects). "ItemContainer" as you can see is custom class, you can't find it somehow. Same with "Item". If you need to find all regular "ItemContainer"-s, you need to loop through all entities on the map