Change:
    public String prefix = Config.Broadcaster.BROADCASTER_PREFIX;
    public List<String> broadcastMessages = Arrays.asList(
            Config.Broadcaster.BROADCASTER_MESSAGES_LIST.toString()
    );
    @Override
    public void run() {
        String message = RandomUtil.nextItem(broadcastMessages);
        for (Player player : Remain.getOnlinePlayers()) {
            Common.tell(player, prefix + message);
        }
    }


To:
    public String prefix = Config.Broadcaster.BROADCASTER_PREFIX;

    @Override
    public void run() {
        String message = RandomUtil.nextItem(Config.Broadcaster.BROADCASTER_MESSAGES_LIST);
        for (Player player : Remain.getOnlinePlayers()) {
            Common.tell(player, prefix + message);
        }
    }