depend: [NextGens]
# or, if NextGens is optional for your plugin
softdepend: [NextGens]

GeneratorAPI api = NextGens.getApi();

NextGens plugin = NextGens.getInstance();

plugin.getHologramManager();    // hologram providers, see below
plugin.getMultiplierRegistry(); // sell multiplier providers, see below
plugin.getGeneratorManager();
plugin.getUserManager();
plugin.getWorthManager();
plugin.getSellwandManager();
plugin.getEventManager();
plugin.getSellManager();
plugin.getRefundManager();

@EventHandler
private void onGenerate(GeneratorGenerateItemEvent event) {
    Player player = Bukkit.getPlayer(event.getOwner());
    if (player == null) {
        return;
    }
    // Double the drop amount for players with a permission
    if (player.hasPermission("myplugin.doubledrops")) {
        event.setDropAmount(event.getDropAmount() * 2);
    }
}

@EventHandler
private void onGenerate(GeneratorGenerateItemEvent event) {
    ActiveGenerator active = event.getActiveGenerator();
    // Instead of dropping the item, handle it yourself
    event.setDropItem(false);
    // Do whatever you want with the drop here
    ItemStack stack = event.getDrop().getItem();
    stack.setAmount(event.getDropAmount());
}

@EventHandler
private void onSell(SellEvent event) {
    Player player = event.getPlayer();
    if (player.getWorld().getName().equalsIgnoreCase("tycoon")) {
        event.setMultiplier(event.getMultiplier() + 0.5);
    }
}

private List<ActiveGenerator> getGenerators(Player player) {
    return NextGens.getApi().getActiveGenerator(player.getUniqueId());
}

private double getWorth(ItemStack stack) {
    Double worth = NextGens.getApi().getWorth(stack);
    // Items without any worth will return null
    return worth == null ? 0.0 : worth;
}

private void giveGenerator(Player player, String generatorId) {
    GeneratorAPI api = NextGens.getApi();
    // Make sure the generator actually exists
    if (api.getGenerator(generatorId) == null) {
        return;
    }
    // If the player's inventory is full, the item will be refunded automatically
    api.giveGenerator(player, generatorId);
}

private void giveSellwand(Player player, double multiplier, int uses) {
    ItemStack sellwand = NextGens.getApi().createSellwand(multiplier, uses);
    player.getInventory().addItem(sellwand);
}

public interface HologramProvider {

    /**
     * The internal id used to match against the config value (holograms.type).
     */
    String id();

    /**
     * The Bukkit plugin name this provider hooks into.
     * Used to detect whether the provider can actually be used.
     */
    String pluginName();

    /**
     * Whether the backing plugin is installed and enabled on this server.
     * Only available providers are eligible for the fallback.
     */
    default boolean isAvailable() {
        return Bukkit.getPluginManager().isPluginEnabled(pluginName());
    }

    void spawn(String name, Location location, List<String> lines);

    void destroy(String name, Location location);
}

public class MyPlugin extends JavaPlugin {

    @Override
    public void onLoad() {
        HologramManager.register(new MyHologramProvider());
    }

}

private void spawnHologram(Location location, List<String> lines) {
    HologramManager manager = NextGens.getInstance().getHologramManager();
    // no hologram plugin is installed, nothing to spawn
    if (!manager.isEnabled()) {
        return;
    }
    manager.getProvider().spawn("my_hologram", location, lines);
}

public class MyMultiplier implements SellMultiplierProvider {

    @Override
    public double getMultiplier(Player player, User user, SellwandData sellwand) {
        // Return the amount to ADD to the multiplier, 0.0 for no change
        if (player.hasPermission("myplugin.vip")) {
            return 0.5;
        }
        return 0.0;
    }

}

@Override
public void onEnable() {
    NextGens.getInstance().getMultiplierRegistry()
            .registerMultiplier(new MyMultiplier());
}