Classe Principal

    private Map<String, SpawnWither> withers = new HashMap<>();

    public SpawnWither getWither(String witherName){
        return withers.get(witherName);
    }

    public void addWither(SpawnWither spawnWither){
        withers.put(spawnWither.getName(), spawnWither);
    }

    public void removeWither(SpawnWither spawnWither){
        withers.remove(spawnWither);
        for (Chunk chunk : spawnWither.getLocation().getWorld().getLoadedChunks()) {
            for(Entity entity : chunk.getEntities()){
                if(entity instanceof Wither){
                    if(entity.getName().equals(spawnWither.getName())){
                        entity.remove();
                    }
                }
            }
        }
    }

    public void deleteAllWithers(){
        withers.clear();
        for(World world : Bukkit.getWorlds()){
            for (Chunk chunk : world.getLoadedChunks()) {
                for(Entity entity : chunk.getEntities()){
                    if(entity instanceof Wither){
                        if(withers.containsKey(entity.getCustomName())){
                            entity.remove();
                        }
                    }
                }
            }
        }
    }

    //exemple d'utilisation
    private void exemple(){
        addWither(new SpawnWither(new Location(Bukkit.getWorld("world"), 0, 0, 0), "§4Team Rouge"));
    }