How can I deny access to people opening chests?

Cancel PlayerInteractEvent if the block clicked was a chest.

 

Code (Text):

public void onInventoryOpen(InventoryOpenEvent event) {
   if (event.getInventory().getType() == InventoryType.CHEST) {
      event.setCancelled(true);
   }
}

What this code is doing, is when you right click a chest, and the menu opens, it calls the InventoryOpenEvent. Here, you are listening for the event, and if the inventory type is equal to a chest, then you cancel the event, therefore not opening the chest.

@PickNChew's method works just as well too.

 

Also you would need a config to store who can open the chest