any way to modify existing instance's fields rather than creating new instances?

[portlek]

node.get(XXXConfig.class, emptyInstance);
this one returns different instances every single time, is there any way to use existing instance to modify the fields only?

[Machine-Maker]

You can get a Mutable ObjectFactory which you can then load an existing instance from a configuration node.

ObjectMapper.Factory factory = (ObjectMapper.Factory) Objects.requireNonNull(node.options().serializers().get(type));
ObjectMapper.Mutable<T> mutable = (ObjectMapper.Mutable<T>) factory.get(type);
mutable.load(instance, node);

[portlek]

is this a right approach?

@SneakyThrows
private void reload(final boolean ensureAsync) {
  if (ensureAsync) {
    PluginExceptions.ensureAsync();
  }
  synchronized (this.lock) {
    final var loader = Configurate.yaml(
      this.directory.resolve("messages.yaml")
    );
    final var node = loader.load();
    final var factory = (ObjectMapper.Factory) Objects.requireNonNull(node.options().serializers().get(AnnouncementMessages2.class));
    final var mutable = (ObjectMapper.Mutable<AnnouncementMessages2>) factory.get(AnnouncementMessages2.class);
    mutable.load(this, node);
    node.set(AnnouncementMessages2.class, this);
    loader.save(node);
  }
}

[zml2008]

That design is strongly discouraged -- it's something you won't be able to do with, say, records, but it is something you can do if you have an existing application you are trying to migrate over.

Note that the specific type returned by the call to TypeSerializerCollection#get is not guaranteed by any api contract, and may change at any point.