only fire PlayerEnterCombatEvent if there are registered listeners for it

src/main/java/me/youhavetrouble/preventstabby/api/event/PlayerEnterCombatEvent.java

@@ -45,4 +45,9 @@ public class PlayerEnterCombatEvent extends Event implements Cancellable {
     public HandlerList getHandlers() {
         return HANDLERS;
     }
+
+    @NotNull
+    public static HandlerList getHandlerList() {
+        return HANDLERS;
+    }
 }