Get things in easy way
// the configuration source
final YamlConfiguration config = new YamlConfiguration();
// result Map
final Map<String, List<Integer>> result = new HashMap<>();
// processing
for (final Map<?, ?> m : config.getMapList("customObjects")) {
final FreeMap map = new FreeMap(m, true); // safe Mode without computing
final String name = map.getString("name");
final FreeList objects = map.getList("ids");
final List<Integer> newList = new ArrayList<>();
for (int i = 0; i < objects.size(); i++) {
final int id = objects.getI(i);
newList.add(id);
}
result.put(name, newList);
}