Cannot cast to chest error

I am trying to 1) Create a chest at a certain block 2)Get a random item from the config and 3)Put said item into the chest. When I use this code I get an error in the task saying that I cannot cast the block to chest. Could you explain to me why this doesn't work?

Methods:

Code:

public static void createRandomChest(){
        Block b = getRandomBlock();
        if(b != null){
            b.setType(Material.CHEST);
            ((Chest) b).getBlockInventory().addItem(ConfigManager.getRandomItem());
        }
    }

    public static Block getRandomBlock(){
        if(chests.size() != 0){
            String randomName = (String) chests.keySet().toArray()[new Random().nextInt(chests.keySet().size())];
            return chests.get(randomName).getBlock();
        }
        return null;
    }

ConfigManager.class:

Code:

private static List<Integer> i;
   
    public ConfigManager(Loot plugin){
        i = plugin.getConfig().getIntegerList("Items");
    }
   
   
   
    @SuppressWarnings("deprecation")
    public static ItemStack getRandomItem(){
        Random random = new Random();
        int rn = random.nextInt(i.size());
        return new ItemStack(Material.getMaterial(i.get(rn)));
    }

Repeating task:

Code:

BukkitScheduler scheduler = getServer().getScheduler();
        scheduler.scheduleSyncRepeatingTask(this, new Runnable() {
            @Override
            public void run() {
                LootManager.createRandomChest();
            }
        }, /*6000*/100, 100/*6000*/);

 

Chests are a more advanced form of a block, they are in fact block states:

Code:

//Does not work because chests are not blocks
((Chest) b).getBlockInventory().addItem(ConfigManager.getRandomItem());

//Hopefully works because chests are BLOCK STATES
((Chest) b.getState()).getBlockInventory().addItem(ConfigManager.getRandomItem());