Impl.java

ExampleEventListener.EVENT
  .registerDeterminator((parameter) -> {
    if (parameter)
      return CANCEL;
    else
      return EXECUTE;
  })
  .registerPayload((parameter) -> {
    parameter.world.killSomebody();
  });

Listener.java

public interface ExampleEventListerner {
  Event<ExampleEventListerner> EVENT = PayloadedEventFactory.createArrayBacked(
    ExampleEventListerner.Determinator.class,
    ExampleEventListener.Payload.class,
    (determinators) -> (parameter) -> {},    
    (payloads) -> (parameter) -> {},
  );
  
  interface Determinator {
    EventResult onExampleEvent(Parameter parameter);
  }
  
  interface Payload {
    void onExampleEvent(Parameter parameter);
  }
}