Main Package

Launcher.java

package main;

import api.YourAPI;

class Launcher extends JavaPlugin {
    private YourAPI api;
    
    @Override
    public void onEnable() {
        api = new YourAPIV1(this);
        api.enable();
        startUpdater();
    }
    
    private void startUpdater() {
        int secondsPerDelay = 30; // 30 seconds for each delay
        int updateDelay = 20 * secondsPerDelay; // server runs at 20 ticks per second
        Bukkit.getServer().getScheduler().scheduleSyncRepeatingTask(getPlugin(), api::updatePeriodically, 0, updateDelay); 
    }
}

YourAPIV1.java

package main;

import api.YourAPI;
import api.buff.BuffModule; // https://gist.github.com/riftrsps/57634ff1f4c8ac58ff7db2d03d3ffcd5#file-buffmodule-java
import api.buff.CommandModule;
import api.quest.QuestModule; // https://gist.github.com/riftrsps/84e2151f0c366b3f9de058442af02aef#file-questmodule-java

public class YourAPIV1 implements YourAPI {
    private final JavaPlugin plugin;
    
    private BuffModule buffModule;
    private CommandModule commandModule;
    private QuestModule questModule;
    
    public YourAPIV1(JavaPlugin plugin) {
        this.plugin = plugin;   
    }
    
    @Override
    public void enable() {
        buffModule = BuffModule.load(this);
        commandModule = CommandModule.load(this);
        questModule = QuestModule.load(this);
        registerListener(buffModule);
        registerListener(commandModule);
        registerListener(questModule);
    }
    
    @Override
    public void registerListener(Listener listener) {
        plugin.getServer().getPluginManager().registerListener(listener, plugin);
    }
    
    @Override
    public void deregisterListener(Listener listener) {
        plugin.getServer().getPluginManager().deregisterListener(listener, plugin);
    }
    
    @Override
    private void updatePeriodically() {
        buffModule.updatePeriodically();
    }
    
    @Override
    public Set<Villager> findVillagersNearby(Entity entity, int radius) {
        return entity.getWorld().getNearbyEntities(entity.getLocation(), radius, radius, radius)
            .stream()
            .filter(e -> e instanceof Villager)
            .map(e -> (Villager) e)
            .peek(v -> buffModule.activateBuffs(v, entity))
            .collect(Collectors.toSet());
    }
}