We don't need the sorted order that a List provides

proxy/src/main/java/com/velocitypowered/proxy/event/EventTypeTracker.java

@@ -17,27 +17,28 @@
 
 package com.velocitypowered.proxy.event;
 
-import com.google.common.collect.ArrayListMultimap;
+import com.google.common.collect.HashMultimap;
 import com.google.common.collect.ImmutableList;
-import com.google.common.collect.ListMultimap;
+import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Multimap;
 import com.google.common.reflect.TypeToken;
-import java.util.List;
+import java.util.Collection;
 import java.util.stream.Collectors;
 
 class EventTypeTracker {
 
-  private final ListMultimap<Class<?>, Class<?>> friends;
+  private final Multimap<Class<?>, Class<?>> friends;
 
   public EventTypeTracker() {
-    this.friends = ArrayListMultimap.create();
+    this.friends = HashMultimap.create();
   }
 
-  public List<Class<?>> getFriendsOf(final Class<?> eventType) {
+  public Collection<Class<?>> getFriendsOf(final Class<?> eventType) {
     if (friends.containsKey(eventType)) {
-      return ImmutableList.copyOf(friends.get(eventType));
+      return ImmutableSet.copyOf(friends.get(eventType));
     }
 
-    final List<Class<?>> types = getEventTypes(eventType);
+    final Collection<Class<?>> types = getEventTypes(eventType);
     for (Class<?> type : types) {
       if (type == eventType) {
         continue;
@@ -48,7 +49,7 @@ class EventTypeTracker {
     return types;
   }
 
-  private static List<Class<?>> getEventTypes(final Class<?> eventType) {
+  private static Collection<Class<?>> getEventTypes(final Class<?> eventType) {
     return TypeToken.of(eventType).getTypes().rawTypes().stream()
         .filter(type -> type != Object.class)
         .collect(Collectors.toList());

proxy/src/main/java/com/velocitypowered/proxy/event/VelocityEventManager.java

@@ -46,6 +46,7 @@ import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
@@ -175,7 +176,7 @@ public class VelocityEventManager implements EventManager {
 
   private @Nullable HandlersCache bakeHandlers(final Class<?> eventType) {
     final List<HandlerRegistration> baked = new ArrayList<>();
-    final List<Class<?>> types = eventTypeTracker.getFriendsOf(eventType);
+    final Collection<Class<?>> types = eventTypeTracker.getFriendsOf(eventType);
 
     lock.readLock().lock();
     try {