Introduce EventGroup

src/main/java/net/minestom/server/event/Event.java

@@ -1,6 +1,7 @@
 package net.minestom.server.event;
 
 import net.minestom.server.event.handler.EventHandler;
+import org.jetbrains.annotations.NotNull;
 
 /**
  * Object which can be listened to by an {@link EventHandler}.
@@ -8,6 +9,10 @@ import net.minestom.server.event.handler.EventHandler;
  * Called using {@link EventHandler#callEvent(Class, Event)}.
  */
 public class Event {
+    public static EventGroup group(@NotNull EventListener<?>... listeners) {
+        return new EventGroup(listeners);
+    }
+
     public static <T extends EntityEvent> EventListener.Builder<T> entity(Class<T> eventType) {
         return new EventListener.Builder<>(eventType);
     }

src/main/java/net/minestom/server/event/EventGroup.java

@@ -0,0 +1,27 @@
+package net.minestom.server.event;
+
+import net.minestom.server.event.handler.EventHandler;
+import org.jetbrains.annotations.NotNull;
+
+public class EventGroup implements ListenerAttach {
+
+    private final EventListener<?>[] listeners;
+
+    protected EventGroup(@NotNull EventListener<?>... listeners) {
+        this.listeners = listeners;
+    }
+
+    @Override
+    public void attachTo(@NotNull EventHandler handler) {
+        for (EventListener<?> listener : listeners) {
+            listener.attachTo(handler);
+        }
+    }
+
+    @Override
+    public void detachFrom(@NotNull EventHandler handler) {
+        for (EventListener<?> listener : listeners) {
+            listener.detachFrom(handler);
+        }
+    }
+}

src/main/java/net/minestom/server/event/EventListener.java

@@ -10,7 +10,7 @@ import java.util.concurrent.CopyOnWriteArraySet;
 import java.util.function.Consumer;
 import java.util.function.Predicate;
 
-public class EventListener<T extends Event> {
+public class EventListener<T extends Event> implements ListenerAttach {
 
     private final Class<T> eventType;
     private final Set<EventHandler> attach = new CopyOnWriteArraySet<>();
@@ -21,6 +21,7 @@ public class EventListener<T extends Event> {
         this.combined = combined;
     }
 
+    @Override
     public void attachTo(@NotNull EventHandler handler) {
         final boolean success = this.attach.add(handler);
         if (success) {
@@ -28,6 +29,7 @@ public class EventListener<T extends Event> {
         }
     }
 
+    @Override
     public void detachFrom(@NotNull EventHandler handler) {
         final boolean success = this.attach.remove(handler);
         if (success) {

src/main/java/net/minestom/server/event/ListenerAttach.java

@@ -0,0 +1,10 @@
+package net.minestom.server.event;
+
+import net.minestom.server.event.handler.EventHandler;
+import org.jetbrains.annotations.NotNull;
+
+public interface ListenerAttach {
+    void attachTo(@NotNull EventHandler handler);
+
+    void detachFrom(@NotNull EventHandler handler);
+}

src/test/java/demo/PlayerInit.java

@@ -143,7 +143,10 @@ public class PlayerInit {
                     .filter(playerChatEvent -> player.isCreative())
                     .handler(playerChatEvent -> Audiences.players().sendMessage(Component.text("Listener is working!")))
                     .build();
-            listener.attachTo(player);
+            //listener.attachTo(player);
+
+            var group = Event.group(listener);
+            group.attachTo(player);
 
         });