Add a better warning message than "Server performance will be affected" for CommandRegisteredEvent use (#10754)

patches/api/0476-Brigadier-based-command-API.patch

@@ -270,16 +270,17 @@ index 0000000000000000000000000000000000000000..6ac205de582983863bd5b3c0fa70d437
 +}
 diff --git a/src/main/java/com/destroystokyo/paper/event/brigadier/CommandRegisteredEvent.java b/src/main/java/com/destroystokyo/paper/event/brigadier/CommandRegisteredEvent.java
 new file mode 100644
-index 0000000000000000000000000000000000000000..8a0c7266cc3fe63d3c6fd83bcd75c54de21038b4
+index 0000000000000000000000000000000000000000..d195c76d9343d2e9e6ade5318ae00470e5c0fe34
 --- /dev/null
 +++ b/src/main/java/com/destroystokyo/paper/event/brigadier/CommandRegisteredEvent.java
-@@ -0,0 +1,169 @@
+@@ -0,0 +1,171 @@
 +package com.destroystokyo.paper.event.brigadier;
 +
 +import com.destroystokyo.paper.brigadier.BukkitBrigadierCommand;
 +import com.mojang.brigadier.tree.ArgumentCommandNode;
 +import com.mojang.brigadier.tree.LiteralCommandNode;
 +import com.mojang.brigadier.tree.RootCommandNode;
++import org.bukkit.Warning;
 +import org.bukkit.command.Command;
 +import org.bukkit.event.Cancellable;
 +import org.bukkit.event.HandlerList;
@@ -299,6 +300,7 @@ index 0000000000000000000000000000000000000000..8a0c7266cc3fe63d3c6fd83bcd75c54d
 + */
 +@ApiStatus.Experimental
 +@Deprecated(since = "1.20.6")
++@Warning(reason = "This event has been superseded by the Commands API and will be removed in a future release. Listen to LifecycleEvents.COMMANDS instead.")
 +public class CommandRegisteredEvent<S extends com.destroystokyo.paper.brigadier.BukkitBrigadierCommandSource> extends ServerEvent implements Cancellable {
 +
 +    private static final HandlerList handlers = new HandlerList();