So it begins...

patches/unapplied/server/0534-Add-sendOpLevel-API.patch

@@ -0,0 +1,51 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Mariell Hoversholm <proximyst@proximyst.com>
+Date: Tue, 29 Dec 2020 15:03:03 +0100
+Subject: [PATCH] Add sendOpLevel API
+
+
+diff --git a/src/main/java/net/minecraft/server/players/PlayerList.java b/src/main/java/net/minecraft/server/players/PlayerList.java
+index 13e2fb9e48ed8722b68b2ce2994d9d84bb22cee4..600bb44d97b477960108ea8cd84a8e734b7e10d0 100644
+--- a/src/main/java/net/minecraft/server/players/PlayerList.java
++++ b/src/main/java/net/minecraft/server/players/PlayerList.java
+@@ -1086,6 +1086,11 @@ public abstract class PlayerList {
+     }
+ 
+     private void sendPlayerPermissionLevel(ServerPlayer player, int permissionLevel) {
++        // Paper start - add recalculatePermissions parameter
++        this.sendPlayerPermissionLevel(player, permissionLevel, true);
++    }
++    public void sendPlayerPermissionLevel(ServerPlayer player, int permissionLevel, boolean recalculatePermissions) {
++        // Paper end
+         if (player.connection != null) {
+             byte b0;
+ 
+@@ -1100,8 +1105,10 @@ public abstract class PlayerList {
+             player.connection.send(new ClientboundEntityEventPacket(player, b0));
+         }
+ 
++        if (recalculatePermissions) { // Paper
+         player.getBukkitEntity().recalculatePermissions(); // CraftBukkit
+         this.server.getCommands().sendCommands(player);
++        } // Paper
+     }
+ 
+     public boolean isWhiteListed(GameProfile profile) {
+diff --git a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
+index 4a363ffbf6ee527b1eaea00e41b3387cb31e70a2..f4ac6130d1112fb908cfd61698207b81d182b492 100644
+--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
++++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
+@@ -638,6 +638,13 @@ public class CraftPlayer extends CraftHumanEntity implements Player {
+             ? (org.bukkit.entity.Firework) entity.getBukkitEntity()
+             : null;
+     }
++
++    @Override
++    public void sendOpLevel(byte level) {
++        Preconditions.checkArgument(level >= 0 && level <= 4, "Level must be within [0, 4]");
++
++        this.getHandle().getServer().getPlayerList().sendPlayerPermissionLevel(this.getHandle(), level, false);
++    }
+     // Paper end
+ 
+     @Override