Fix Bukkit command map access (#2229)

bukkit/src/main/java/me/lucko/luckperms/bukkit/BukkitAsyncCommandExecutor.java

@@ -27,6 +27,7 @@ package me.lucko.luckperms.bukkit;
 
 import com.destroystokyo.paper.event.server.AsyncTabCompleteEvent;
 
+import me.lucko.luckperms.bukkit.util.CommandMapUtil;
 import me.lucko.luckperms.common.command.utils.ArgumentTokenizer;
 import me.lucko.luckperms.common.sender.Sender;
 
@@ -62,7 +63,7 @@ public class BukkitAsyncCommandExecutor extends BukkitCommandExecutor {
         }
 
         String commandLabel = buffer.substring(0, firstSpace);
-        Command command = this.plugin.getBootstrap().getServer().getCommandMap().getCommand(commandLabel);
+        Command command = CommandMapUtil.getCommandMap(this.plugin.getBootstrap().getServer()).getCommand(commandLabel);
         if (command != this.command) {
             return;
         }

bukkit/src/main/java/me/lucko/luckperms/bukkit/BukkitCommandExecutor.java

@@ -25,6 +25,7 @@
 
 package me.lucko.luckperms.bukkit;
 
+import me.lucko.luckperms.bukkit.util.CommandMapUtil;
 import me.lucko.luckperms.common.command.CommandManager;
 import me.lucko.luckperms.common.command.utils.ArgumentTokenizer;
 import me.lucko.luckperms.common.config.ConfigKeys;
@@ -113,7 +114,7 @@ public class BukkitCommandExecutor extends CommandManager implements CommandExec
             commandLabel = buffer.substring(0, firstSpace);
         }
 
-        Command command = this.plugin.getBootstrap().getServer().getCommandMap().getCommand(commandLabel);
+        Command command = CommandMapUtil.getCommandMap(this.plugin.getBootstrap().getServer()).getCommand(commandLabel);
         if (command != this.command) {
             return;
         }

bukkit/src/main/java/me/lucko/luckperms/bukkit/util/CommandMapUtil.java

@@ -0,0 +1,56 @@
+/*
+ * This file is part of LuckPerms, licensed under the MIT License.
+ *
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  Permission is hereby granted, free of charge, to any person obtaining a copy
+ *  of this software and associated documentation files (the "Software"), to deal
+ *  in the Software without restriction, including without limitation the rights
+ *  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ *  copies of the Software, and to permit persons to whom the Software is
+ *  furnished to do so, subject to the following conditions:
+ *
+ *  The above copyright notice and this permission notice shall be included in all
+ *  copies or substantial portions of the Software.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ *  SOFTWARE.
+ */
+
+package me.lucko.luckperms.bukkit.util;
+
+import org.bukkit.Server;
+import org.bukkit.command.CommandMap;
+import org.bukkit.plugin.SimplePluginManager;
+
+import java.lang.reflect.Field;
+
+public final class CommandMapUtil {
+    private CommandMapUtil() {}
+
+    private static final Field COMMAND_MAP_FIELD;
+
+    static {
+        try {
+            COMMAND_MAP_FIELD = SimplePluginManager.class.getDeclaredField("commandMap");
+            COMMAND_MAP_FIELD.setAccessible(true);
+        } catch (NoSuchFieldException e) {
+            throw new ExceptionInInitializerError(e);
+        }
+    }
+
+    public static CommandMap getCommandMap(Server server) {
+        try {
+            return (CommandMap) COMMAND_MAP_FIELD.get(server.getPluginManager());
+        } catch (Exception e) {
+            throw new RuntimeException("Could not get CommandMap", e);
+        }
+    }
+
+}