private void initializeEconomy() {
        if (plugin.getServer().getPluginManager().getPlugin("Vault") == null) {
            throw new IllegalStateException("Vault plugin not found!");
        }
        RegisteredServiceProvider<Economy> provider =
                plugin.getServer().getServicesManager().getRegistration(Economy.class);
        if (provider == null) {
            throw new IllegalStateException("Service provider not found.");
        }
        economy = provider.getProvider();
        if (economy == null) {
            throw new IllegalStateException("Economy can't be initialized.");
        }
    }