@EventHandler
    public void onPlayerInteract(final PlayerInteractEvent event) {
        final Action action = event.getAction();
        final Player player = event.getPlayer();
        final Block block = event.getClickedBlock();
        final BlockRegistry blockRegistry = BlockRegistry.getInstance();

        if (player.getItemInHand().getType() == Material.DIAMOND) {
            if (action == Action.RIGHT_CLICK_BLOCK) {
                System.out.println("isRegistered: " + blockRegistry.isRegistered(block));
                if (blockRegistry.isRegistered(block)) {
                    blockRegistry.increaseLevel(block);
                    Common.tell(player, "&bIncreased the &a" + block.getType() + " &bblock's level to lvl &a" + blockRegistry.getLevel(block) + ".");
                }
            }
        }
    }