RxJava support

This starter supports RxJava for event listeners, it's really easy to get started:

Define the dependency in your pom.xml:

<dependency>
    <groupId>io.reactivex.rxjava2</groupId>
    <artifactId>rxjava</artifactId>
    <version>2.2.8</version>
</dependency>

And done! The starter will automatically detect the dependency and setup everything for you.

To create a observable for a specific event, you can use:

@Component
public class TestListener {

    @ObserveEvent
    private Observable<PlayerJoinEvent> joinEventObservable;

}

After that, you can manipulate the observable in any way you want:

joinEventObservable
    .filter(event -> event.getPlayer().isOp())
    .subscribe(event -> event.getPlayer().sendMessage("hello operator!"));