Fix toLowerCase/toUpperCase locale sensitivity

api/src/main/java/net/luckperms/api/node/ChatMetaType.java

@@ -31,6 +31,8 @@ import net.luckperms.api.node.types.SuffixNode;
 
 import org.checkerframework.checker.nullness.qual.NonNull;
 
+import java.util.Locale;
+
 /**
  * Represents a type of chat meta
  */
@@ -70,7 +72,7 @@ public enum ChatMetaType {
     private final NodeType<? extends ChatMetaNode<?, ?>> nodeType;
 
     ChatMetaType(NodeType<? extends ChatMetaNode<?, ?>> nodeType) {
-        this.name = nodeType.name().toLowerCase();
+        this.name = nodeType.name().toLowerCase(Locale.ROOT);
         this.nodeType = nodeType;
     }
 

api/src/main/java/net/luckperms/api/node/metadata/SimpleNodeMetadataKey.java

@@ -27,6 +27,7 @@ package net.luckperms.api.node.metadata;
 
 import org.checkerframework.checker.nullness.qual.NonNull;
 
+import java.util.Locale;
 import java.util.Objects;
 
 final class SimpleNodeMetadataKey<T> implements NodeMetadataKey<T> {
@@ -34,7 +35,7 @@ final class SimpleNodeMetadataKey<T> implements NodeMetadataKey<T> {
     private final Class<T> type;
 
     SimpleNodeMetadataKey(String name, Class<T> type) {
-        this.name = name.toLowerCase();
+        this.name = name.toLowerCase(Locale.ROOT);
         this.type = type;
     }
 

api/src/main/java/net/luckperms/api/query/SimpleOptionKey.java

@@ -27,6 +27,7 @@ package net.luckperms.api.query;
 
 import org.checkerframework.checker.nullness.qual.NonNull;
 
+import java.util.Locale;
 import java.util.Objects;
 
 final class SimpleOptionKey<T> implements OptionKey<T> {
@@ -35,7 +36,7 @@ final class SimpleOptionKey<T> implements OptionKey<T> {
     private final int hashCode;
 
     SimpleOptionKey(String name, Class<T> type) {
-        this.name = name.toLowerCase();
+        this.name = name.toLowerCase(Locale.ROOT);
         this.type = type;
         this.hashCode = Objects.hash(this.name, this.type); // cache hashcode
     }

bukkit/src/main/java/me/lucko/luckperms/bukkit/inject/permissible/LuckPermsPermissionAttachment.java

@@ -46,6 +46,7 @@ import java.lang.reflect.Field;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Set;
@@ -239,7 +240,7 @@ public class LuckPermsPermissionAttachment extends PermissionAttachment {
         Objects.requireNonNull(name, "name is null");
         Preconditions.checkArgument(!name.isEmpty(), "name is empty");
 
-        String permission = name.toLowerCase();
+        String permission = name.toLowerCase(Locale.ROOT);
 
         Boolean previous = this.perms.put(permission, value);
         if (previous != null && previous == value) {
@@ -264,7 +265,7 @@ public class LuckPermsPermissionAttachment extends PermissionAttachment {
         Objects.requireNonNull(name, "name is null");
         Preconditions.checkArgument(!name.isEmpty(), "name is empty");
 
-        String permission = name.toLowerCase();
+        String permission = name.toLowerCase(Locale.ROOT);
 
         Boolean previous = this.perms.remove(permission);
         if (previous == null) {

bukkit/src/main/java/me/lucko/luckperms/bukkit/inject/server/LuckPermsDefaultsMap.java

@@ -43,6 +43,7 @@ import org.checkerframework.checker.nullness.qual.NonNull;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
@@ -140,7 +141,7 @@ public final class LuckPermsDefaultsMap implements Map<Boolean, Set<Permission>>
         protected @NonNull Map<String, Boolean> supply() {
             Map<String, Boolean> builder = new HashMap<>();
             for (Permission perm : LuckPermsDefaultsMap.this.get(this.op)) {
-                String name = perm.getName().toLowerCase();
+                String name = perm.getName().toLowerCase(Locale.ROOT);
                 builder.put(name, true);
                 for (Map.Entry<String, Boolean> child : LuckPermsDefaultsMap.this.plugin.getPermissionMap().getChildPermissions(name, true).entrySet()) {
                     builder.putIfAbsent(child.getKey(), child.getValue());

bukkit/src/main/java/me/lucko/luckperms/bukkit/inject/server/LuckPermsPermissionMap.java

@@ -40,6 +40,7 @@ import org.checkerframework.checker.nullness.qual.Nullable;
 import java.lang.reflect.Field;
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
 import java.util.concurrent.ConcurrentHashMap;
@@ -180,7 +181,7 @@ public final class LuckPermsPermissionMap extends ForwardingMap<String, Permissi
                 continue;
             }
 
-            String key = e.getKey().toLowerCase();
+            String key = e.getKey().toLowerCase(Locale.ROOT);
 
             if (accumulator.containsKey(key)) {
                 continue; // Prevent infinite loops

bukkit/src/main/java/me/lucko/luckperms/bukkit/listeners/BukkitPlatformListener.java

@@ -38,6 +38,7 @@ import org.bukkit.event.server.PluginEnableEvent;
 import org.bukkit.event.server.RemoteServerCommandEvent;
 import org.bukkit.event.server.ServerCommandEvent;
 
+import java.util.Locale;
 import java.util.regex.Pattern;
 
 public class BukkitPlatformListener implements Listener {
@@ -51,17 +52,17 @@ public class BukkitPlatformListener implements Listener {
 
     @EventHandler(ignoreCancelled = true)
     public void onPlayerCommand(PlayerCommandPreprocessEvent e) {
-        handleCommand(e.getPlayer(), e.getMessage().toLowerCase(), e);
+        handleCommand(e.getPlayer(), e.getMessage().toLowerCase(Locale.ROOT), e);
     }
 
     @EventHandler(ignoreCancelled = true)
     public void onServerCommand(ServerCommandEvent e) {
-        handleCommand(e.getSender(), e.getCommand().toLowerCase(), e);
+        handleCommand(e.getSender(), e.getCommand().toLowerCase(Locale.ROOT), e);
     }
 
     @EventHandler(ignoreCancelled = true)
     public void onRemoteServerCommand(RemoteServerCommandEvent e) {
-        handleCommand(e.getSender(), e.getCommand().toLowerCase(), e);
+        handleCommand(e.getSender(), e.getCommand().toLowerCase(Locale.ROOT), e);
     }
 
     private void handleCommand(CommandSender sender, String cmdLine, Cancellable event) {

bukkit/src/main/java/me/lucko/luckperms/bukkit/vault/LuckPermsVaultChat.java

@@ -49,6 +49,7 @@ import net.luckperms.api.query.Flag;
 import net.luckperms.api.query.QueryOptions;
 import net.milkbowl.vault.chat.Chat;
 
+import java.util.Locale;
 import java.util.Objects;
 import java.util.UUID;
 
@@ -254,7 +255,7 @@ public class LuckPermsVaultChat extends AbstractVaultChat {
 
     private void setMeta(PermissionHolder holder, String key, Object value, String world) {
         if (key.equalsIgnoreCase(Prefix.NODE_KEY) || key.equalsIgnoreCase(Suffix.NODE_KEY)) {
-            setChatMeta(holder, ChatMetaType.valueOf(key.toUpperCase()), value == null ? null : value.toString(), world);
+            setChatMeta(holder, ChatMetaType.valueOf(key.toUpperCase(Locale.ROOT)), value == null ? null : value.toString(), world);
             return;
         }
 
@@ -277,7 +278,7 @@ public class LuckPermsVaultChat extends AbstractVaultChat {
     private QueryOptions createQueryOptionsForWorldSet(String world) {
         ImmutableContextSet.Builder context = new ImmutableContextSetImpl.BuilderImpl();
         if (world != null && !world.isEmpty() && !world.equalsIgnoreCase("global")) {
-            context.add(DefaultContextKeys.WORLD_KEY, world.toLowerCase());
+            context.add(DefaultContextKeys.WORLD_KEY, world.toLowerCase(Locale.ROOT));
         }
         context.add(DefaultContextKeys.SERVER_KEY, this.vaultPermission.getVaultServer());
 

bukkit/src/main/java/me/lucko/luckperms/bukkit/vault/LuckPermsVaultPermission.java

@@ -59,6 +59,7 @@ import net.milkbowl.vault.permission.Permission;
 import org.bukkit.entity.Player;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
+import java.util.Locale;
 import java.util.Objects;
 import java.util.Optional;
 import java.util.UUID;
@@ -348,7 +349,7 @@ public class LuckPermsVaultPermission extends AbstractVaultPermission {
             // remove already accumulated worlds
             context.removeAll(DefaultContextKeys.WORLD_KEY);
             // add the vault world
-            context.add(DefaultContextKeys.WORLD_KEY, world.toLowerCase());
+            context.add(DefaultContextKeys.WORLD_KEY, world.toLowerCase(Locale.ROOT));
         }
 
         // if we're using a special vault server

common/src/main/java/me/lucko/luckperms/common/actionlog/LoggedAction.java

@@ -47,6 +47,7 @@ import java.time.Duration;
 import java.time.Instant;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Locale;
 import java.util.Objects;
 import java.util.Optional;
 import java.util.UUID;
@@ -126,10 +127,10 @@ public class LoggedAction implements Action {
     }
 
     public boolean matchesSearch(String query) {
-        query = Objects.requireNonNull(query, "query").toLowerCase();
+        query = Objects.requireNonNull(query, "query").toLowerCase(Locale.ROOT);
-        return this.source.name.toLowerCase().contains(query) ||
+        return this.source.name.toLowerCase(Locale.ROOT).contains(query) ||
-                this.target.name.toLowerCase().contains(query) ||
+                this.target.name.toLowerCase(Locale.ROOT).contains(query) ||
-                this.description.toLowerCase().contains(query);
+                this.description.toLowerCase(Locale.ROOT).contains(query);
     }
 
     public void submit(LuckPermsPlugin plugin, Sender sender) {

common/src/main/java/me/lucko/luckperms/common/api/ApiUtils.java

@@ -31,6 +31,7 @@ import me.lucko.luckperms.common.config.ConfigKeys;
 import me.lucko.luckperms.common.plugin.LuckPermsPlugin;
 import me.lucko.luckperms.common.storage.misc.DataConstraints;
 
+import java.util.Locale;
 import java.util.function.Predicate;
 
 public final class ApiUtils {
@@ -55,7 +56,7 @@ public final class ApiUtils {
         }
 
         Preconditions.checkArgument(DataConstraints.GROUP_NAME_TEST.test(s), "Invalid name entry: " + s);
-        return s.toLowerCase();
+        return s.toLowerCase(Locale.ROOT);
     }
 
 }

common/src/main/java/me/lucko/luckperms/common/api/implementation/ApiUser.java

@@ -38,6 +38,7 @@ import net.luckperms.api.node.NodeEqualityPredicate;
 
 import org.checkerframework.checker.nullness.qual.NonNull;
 
+import java.util.Locale;
 import java.util.Objects;
 import java.util.UUID;
 
@@ -83,11 +84,11 @@ public class ApiUser extends ApiPermissionHolder implements net.luckperms.api.mo
             return DataMutateResult.FAIL_ALREADY_HAS;
         }
 
-        if (!this.handle.hasNode(DataType.NORMAL, Inheritance.builder(group.toLowerCase()).build(), NodeEqualityPredicate.IGNORE_EXPIRY_TIME_AND_VALUE).asBoolean()) {
+        if (!this.handle.hasNode(DataType.NORMAL, Inheritance.builder(group.toLowerCase(Locale.ROOT)).build(), NodeEqualityPredicate.IGNORE_EXPIRY_TIME_AND_VALUE).asBoolean()) {
             return DataMutateResult.FAIL;
         }
 
-        this.handle.getPrimaryGroup().setStoredValue(group.toLowerCase());
+        this.handle.getPrimaryGroup().setStoredValue(group.toLowerCase(Locale.ROOT));
         return DataMutateResult.SUCCESS;
     }
 

common/src/main/java/me/lucko/luckperms/common/backup/Importer.java

@@ -50,6 +50,7 @@ import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Set;
 import java.util.UUID;
@@ -167,7 +168,7 @@ public class Importer implements Runnable {
         for (JsonElement holderElement : holdersArray) {
             JsonObject jsonData = holderElement.getAsJsonObject();
 
-            HolderType type = HolderType.valueOf(jsonData.get("type").getAsString().toUpperCase());
+            HolderType type = HolderType.valueOf(jsonData.get("type").getAsString().toUpperCase(Locale.ROOT));
             String id = jsonData.get("id").getAsString();
 
             if (type == HolderType.GROUP) {

common/src/main/java/me/lucko/luckperms/common/bulkupdate/query/QueryField.java

@@ -25,6 +25,8 @@
 
 package me.lucko.luckperms.common.bulkupdate.query;
 
+import java.util.Locale;
+
 /**
  * Represents a field being used in an update
  */
@@ -38,7 +40,7 @@ public enum QueryField {
 
     public static QueryField of(String s) {
         try {
-            return valueOf(s.toUpperCase());
+            return valueOf(s.toUpperCase(Locale.ROOT));
         } catch (IllegalArgumentException e) {
             return null;
         }

common/src/main/java/me/lucko/luckperms/common/cacheddata/type/SimpleMetaCache.java

@@ -45,6 +45,7 @@ import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
 import java.util.SortedMap;
@@ -108,7 +109,7 @@ public class SimpleMetaCache extends UsageTracked implements CachedMetaData {
 
     public String getMetaValue(String key, MetaCheckEvent.Origin origin) {
         Objects.requireNonNull(key, "key");
-        return this.flattenedMeta.get(key.toLowerCase());
+        return this.flattenedMeta.get(key.toLowerCase(Locale.ROOT));
     }
 
     @Override
@@ -205,7 +206,7 @@ public class SimpleMetaCache extends UsageTracked implements CachedMetaData {
             }
 
             String key = (String) k;
-            return super.get(key.toLowerCase());
+            return super.get(key.toLowerCase(Locale.ROOT));
         }
     }
 

common/src/main/java/me/lucko/luckperms/common/cacheddata/type/SimpleMetaValueSelector.java

@@ -30,6 +30,7 @@ import net.luckperms.api.query.meta.MetaValueSelector;
 import org.checkerframework.checker.nullness.qual.NonNull;
 
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 
 public class SimpleMetaValueSelector implements MetaValueSelector {
@@ -81,7 +82,7 @@ public class SimpleMetaValueSelector implements MetaValueSelector {
 
         public static Strategy parse(String s) {
             try {
-                return Strategy.valueOf(s.replace('-', '_').toUpperCase());
+                return Strategy.valueOf(s.replace('-', '_').toUpperCase(Locale.ROOT));
             } catch (IllegalArgumentException e) {
                 return null;
             }

common/src/main/java/me/lucko/luckperms/common/calculator/PermissionCalculator.java

@@ -35,6 +35,7 @@ import me.lucko.luckperms.common.verbose.event.PermissionCheckEvent;
 import org.checkerframework.checker.nullness.qual.NonNull;
 
 import java.util.Collection;
+import java.util.Locale;
 import java.util.Map;
 import java.util.function.Function;
 
@@ -85,7 +86,7 @@ public class PermissionCalculator implements Function<String, TristateResult> {
     public TristateResult apply(@NonNull String permission) {
         // convert the permission to lowercase, as all values in the backing map are also lowercase.
         // this allows fast case insensitive lookups
-        permission = permission.toLowerCase();
+        permission = permission.toLowerCase(Locale.ROOT);
 
         // offer the permission to the permission vault
         // we only need to do this once per permission, so it doesn't matter

common/src/main/java/me/lucko/luckperms/common/command/CommandManager.java

@@ -75,6 +75,7 @@ import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutorService;
@@ -130,7 +131,7 @@ public class CommandManager {
                 .add(new ListTracks())
                 .build()
                 .stream()
-                .collect(ImmutableCollectors.toMap(c -> c.getName().toLowerCase(), Function.identity()));
+                .collect(ImmutableCollectors.toMap(c -> c.getName().toLowerCase(Locale.ROOT), Function.identity()));
     }
 
     public LuckPermsPlugin getPlugin() {
@@ -235,7 +236,7 @@ public class CommandManager {
         }
 
         // Look for the main command.
-        Command<?> main = this.mainCommands.get(arguments.get(0).toLowerCase());
+        Command<?> main = this.mainCommands.get(arguments.get(0).toLowerCase(Locale.ROOT));
 
         // Main command not found
         if (main == null) {
@@ -276,7 +277,7 @@ public class CommandManager {
                 .collect(Collectors.toList());
 
         return TabCompleter.create()
-                .at(0, CompletionSupplier.startsWith(() -> mains.stream().map(c -> c.getName().toLowerCase())))
+                .at(0, CompletionSupplier.startsWith(() -> mains.stream().map(c -> c.getName().toLowerCase(Locale.ROOT))))
                 .from(1, partial -> mains.stream()
                         .filter(m -> m.getName().equalsIgnoreCase(arguments.get(0)))
                         .findFirst()
@@ -333,7 +334,7 @@ public class CommandManager {
         // '/lp user Luck p set --> /lp user Luck permission set' etc
         //                ^                       ^^^^^^^^^^
         if (args.size() >= 3 && (rewriteLastArgument || args.size() >= 4)) {
-            String arg0 = args.get(0).toLowerCase();
+            String arg0 = args.get(0).toLowerCase(Locale.ROOT);
             if (arg0.equals("user") || arg0.equals("group")) {
                 replaceArgs(args, 2, arg -> {
                     switch (arg) {
@@ -353,7 +354,7 @@ public class CommandManager {
                 // '/lp user Luck permission i' --> '/lp user Luck permission info' etc
                 //                           ^                                ^^^^
                 if (args.size() >= 4 && (rewriteLastArgument || args.size() >= 5)) {
-                    String arg2 = args.get(2).toLowerCase();
+                    String arg2 = args.get(2).toLowerCase(Locale.ROOT);
                     if (arg2.equals("permission") || arg2.equals("parent") || arg2.equals("meta")) {
                         replaceArgs(args, 3, arg -> arg.equals("i") ? "info" : null);
                     }
@@ -363,7 +364,7 @@ public class CommandManager {
     }
 
     private static void replaceArgs(List<String> args, int i, Function<String, String> rewrites) {
-        String arg = args.get(i).toLowerCase();
+        String arg = args.get(i).toLowerCase(Locale.ROOT);
         String rewrite = rewrites.apply(arg);
         if (rewrite != null) {
             args.remove(i);

common/src/main/java/me/lucko/luckperms/common/command/abstraction/ChildCommand.java

@@ -36,6 +36,7 @@ import net.kyori.adventure.text.TextComponent;
 import net.kyori.adventure.text.format.NamedTextColor;
 
 import java.util.List;
+import java.util.Locale;
 import java.util.function.Predicate;
 import java.util.stream.Collectors;
 
@@ -58,7 +59,7 @@ public abstract class ChildCommand<T> extends Command<T> {
         TextComponent.Builder builder = Component.text()
                 .append(Component.text('>', NamedTextColor.DARK_AQUA))
                 .append(Component.space())
-                .append(Component.text(getName().toLowerCase(), NamedTextColor.GREEN));
+                .append(Component.text(getName().toLowerCase(Locale.ROOT), NamedTextColor.GREEN));
 
         if (getArgs().isPresent()) {
             List<Component> argUsages = getArgs().get().stream()

common/src/main/java/me/lucko/luckperms/common/command/abstraction/GenericChildCommand.java

@@ -41,6 +41,7 @@ import net.kyori.adventure.text.format.NamedTextColor;
 
 import java.util.Collections;
 import java.util.List;
+import java.util.Locale;
 import java.util.function.Predicate;
 import java.util.stream.Collectors;
 
@@ -106,7 +107,7 @@ public abstract class GenericChildCommand {
         TextComponent.Builder builder = Component.text()
                 .append(Component.text('>', NamedTextColor.DARK_AQUA))
                 .append(Component.space())
-                .append(Component.text(getName().toLowerCase(), NamedTextColor.GREEN));
+                .append(Component.text(getName().toLowerCase(Locale.ROOT), NamedTextColor.GREEN));
 
         if (getArgs() != null) {
             List<Component> argUsages = getArgs().stream()

common/src/main/java/me/lucko/luckperms/common/command/abstraction/GenericParentCommand.java

@@ -38,6 +38,7 @@ import me.lucko.luckperms.common.util.Predicates;
 
 import java.util.Collections;
 import java.util.List;
+import java.util.Locale;
 import java.util.stream.Collectors;
 
 /**
@@ -96,7 +97,7 @@ public class GenericParentCommand<T extends PermissionHolder> extends ChildComma
         return TabCompleter.create()
                 .at(0, CompletionSupplier.startsWith(() -> this.children.stream()
                         .filter(s -> s.isAuthorized(sender, this.type))
-                        .map(s -> s.getName().toLowerCase())
+                        .map(s -> s.getName().toLowerCase(Locale.ROOT))
                 ))
                 .from(1, partial -> this.children.stream()
                         .filter(s -> s.isAuthorized(sender, this.type))
@@ -121,10 +122,10 @@ public class GenericParentCommand<T extends PermissionHolder> extends ChildComma
         if (!subs.isEmpty()) {
             switch (this.type) {
                 case USER:
-                    Message.MAIN_COMMAND_USAGE_HEADER.send(sender, getName(), String.format("/%s user <user> " + getName().toLowerCase(), label));
+                    Message.MAIN_COMMAND_USAGE_HEADER.send(sender, getName(), String.format("/%s user <user> " + getName().toLowerCase(Locale.ROOT), label));
                     break;
                 case GROUP:
-                    Message.MAIN_COMMAND_USAGE_HEADER.send(sender, getName(), String.format("/%s group <group> " + getName().toLowerCase(), label));
+                    Message.MAIN_COMMAND_USAGE_HEADER.send(sender, getName(), String.format("/%s group <group> " + getName().toLowerCase(Locale.ROOT), label));
                     break;
                 default:
                     throw new AssertionError(this.type);

common/src/main/java/me/lucko/luckperms/common/command/abstraction/ParentCommand.java

@@ -38,6 +38,7 @@ import org.checkerframework.checker.nullness.qual.NonNull;
 
 import java.util.Collections;
 import java.util.List;
+import java.util.Locale;
 import java.util.concurrent.locks.ReentrantLock;
 import java.util.stream.Collectors;
 
@@ -123,7 +124,7 @@ public abstract class ParentCommand<T, I> extends Command<Void> {
                         .at(0, CompletionSupplier.startsWith(() -> getTargets(plugin).stream()))
                         .at(1, CompletionSupplier.startsWith(() -> getChildren().stream()
                                 .filter(s -> s.isAuthorized(sender))
-                                .map(s -> s.getName().toLowerCase())
+                                .map(s -> s.getName().toLowerCase(Locale.ROOT))
                         ))
                         .from(2, partial -> getChildren().stream()
                                 .filter(s -> s.isAuthorized(sender))
@@ -137,7 +138,7 @@ public abstract class ParentCommand<T, I> extends Command<Void> {
                 return TabCompleter.create()
                         .at(0, CompletionSupplier.startsWith(() -> getChildren().stream()
                                 .filter(s -> s.isAuthorized(sender))
-                                .map(s -> s.getName().toLowerCase())
+                                .map(s -> s.getName().toLowerCase(Locale.ROOT))
                         ))
                         .from(1, partial -> getChildren().stream()
                                 .filter(s -> s.isAuthorized(sender))

common/src/main/java/me/lucko/luckperms/common/command/abstraction/SingleCommand.java

@@ -38,6 +38,7 @@ import net.kyori.adventure.text.TextComponent;
 import net.kyori.adventure.text.format.NamedTextColor;
 
 import java.util.List;
+import java.util.Locale;
 import java.util.function.Predicate;
 import java.util.stream.Collectors;
 
@@ -62,7 +63,7 @@ public abstract class SingleCommand extends Command<Void> {
         TextComponent.Builder builder = Component.text()
                 .append(Component.text('>', NamedTextColor.DARK_AQUA))
                 .append(Component.space())
-                .append(Component.text(getName().toLowerCase(), NamedTextColor.GREEN));
+                .append(Component.text(getName().toLowerCase(Locale.ROOT), NamedTextColor.GREEN));
 
         if (getArgs().isPresent()) {
             List<Component> argUsages = getArgs().get().stream()

common/src/main/java/me/lucko/luckperms/common/command/spec/CommandSpec.java

@@ -31,6 +31,7 @@ import net.kyori.adventure.text.Component;
 
 import java.util.Arrays;
 import java.util.List;
+import java.util.Locale;
 
 /**
  * An enumeration of the command defintion/usage messages used in the plugin.
@@ -437,7 +438,7 @@ public enum CommandSpec {
     }
 
     public String key() {
-        return name().toLowerCase().replace('_', '-');
+        return name().toLowerCase(Locale.ROOT).replace('_', '-');
     }
 
     private static PartialArgument arg(String id, String name, boolean required) {

common/src/main/java/me/lucko/luckperms/common/command/tabcomplete/TabCompleter.java

@@ -29,6 +29,7 @@ import com.google.common.base.Preconditions;
 
 import java.util.HashMap;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.function.Predicate;
 
@@ -112,7 +113,7 @@ public class TabCompleter {
             if (string.length() < substring.length()) {
                 return false;
             }
-            return string.toLowerCase().contains(substring.toLowerCase());
+            return string.toLowerCase(Locale.ROOT).contains(substring.toLowerCase(Locale.ROOT));
         };
     }
 

common/src/main/java/me/lucko/luckperms/common/command/tabcomplete/TabCompletions.java

@@ -36,6 +36,7 @@ import net.luckperms.api.context.ImmutableContextSet;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
+import java.util.Locale;
 import java.util.Set;
 import java.util.stream.Collectors;
 
@@ -57,7 +58,7 @@ public final class TabCompletions {
         this.permissions = partial -> {
             PermissionRegistry cache = plugin.getPermissionRegistry();
 
-            String start = partial.toLowerCase();
+            String start = partial.toLowerCase(Locale.ROOT);
             List<String> parts = new ArrayList<>(Splitter.on('.').splitToList(start));
             TreeNode root = cache.getRootNode();
 

common/src/main/java/me/lucko/luckperms/common/command/utils/ArgumentList.java

@@ -47,6 +47,7 @@ import java.time.Duration;
 import java.time.Instant;
 import java.time.temporal.ChronoUnit;
 import java.util.List;
+import java.util.Locale;
 import java.util.Optional;
 import java.util.UUID;
 import java.util.function.Predicate;
@@ -101,7 +102,7 @@ public class ArgumentList extends ForwardingList<String> {
     }
 
     public String getLowercase(int index, Predicate<? super String> test) throws ArgumentException.DetailedUsage {
-        String arg = get(index).toLowerCase();
+        String arg = get(index).toLowerCase(Locale.ROOT);
         if (!test.test(arg)) {
             throw new ArgumentException.DetailedUsage();
         }
@@ -188,7 +189,7 @@ public class ArgumentList extends ForwardingList<String> {
     }
 
     private static TemporaryNodeMergeStrategy parseTemporaryModifier(String s) {
-        switch (s.toLowerCase()) {
+        switch (s.toLowerCase(Locale.ROOT)) {
             case "accumulate":
                 return TemporaryNodeMergeStrategy.ADD_NEW_DURATION_TO_EXISTING;
             case "replace":

common/src/main/java/me/lucko/luckperms/common/command/utils/SortType.java

@@ -25,6 +25,8 @@
 
 package me.lucko.luckperms.common.command.utils;
 
+import java.util.Locale;
+
 public enum SortType {
 
     PRIORITY,
@@ -32,6 +34,6 @@ public enum SortType {
 
     @Override
     public String toString() {
-        return name().toLowerCase();
+        return name().toLowerCase(Locale.ROOT);
     }
 }

common/src/main/java/me/lucko/luckperms/common/commands/generic/meta/MetaAddChatMeta.java

@@ -47,6 +47,7 @@ import net.luckperms.api.model.data.DataType;
 import net.luckperms.api.node.ChatMetaType;
 
 import java.util.List;
+import java.util.Locale;
 
 public class MetaAddChatMeta extends GenericChildCommand {
 
@@ -99,7 +100,7 @@ public class MetaAddChatMeta extends GenericChildCommand {
             Message.ADD_CHATMETA_SUCCESS.send(sender, target, this.type, meta, priority, context);
 
             LoggedAction.build().source(sender).target(target)
-                    .description("meta" , "add" + this.type.name().toLowerCase(), priority, meta, context)
+                    .description("meta" , "add" + this.type.name().toLowerCase(Locale.ROOT), priority, meta, context)
                     .build().submit(plugin, sender);
 
             StorageAssistant.save(target, sender, plugin);

common/src/main/java/me/lucko/luckperms/common/commands/generic/meta/MetaAddTempChatMeta.java

@@ -50,6 +50,7 @@ import net.luckperms.api.node.ChatMetaType;
 
 import java.time.Duration;
 import java.util.List;
+import java.util.Locale;
 
 public class MetaAddTempChatMeta extends GenericChildCommand {
 
@@ -107,7 +108,7 @@ public class MetaAddTempChatMeta extends GenericChildCommand {
             Message.ADD_TEMP_CHATMETA_SUCCESS.send(sender, target, this.type, meta, priority, duration, context);
 
             LoggedAction.build().source(sender).target(target)
-                    .description("meta" , "addtemp" + this.type.name().toLowerCase(), priority, meta, duration, context)
+                    .description("meta" , "addtemp" + this.type.name().toLowerCase(Locale.ROOT), priority, meta, duration, context)
                     .build().submit(plugin, sender);
 
             StorageAssistant.save(target, sender, plugin);

common/src/main/java/me/lucko/luckperms/common/commands/generic/meta/MetaClear.java

@@ -46,6 +46,7 @@ import net.luckperms.api.model.data.DataType;
 import net.luckperms.api.node.NodeType;
 
 import java.util.List;
+import java.util.Locale;
 
 public class MetaClear extends GenericChildCommand {
     public MetaClear() {
@@ -61,7 +62,7 @@ public class MetaClear extends GenericChildCommand {
 
         NodeType<?> type = null;
         if (!args.isEmpty()) {
-            String typeId = args.get(0).toLowerCase();
+            String typeId = args.get(0).toLowerCase(Locale.ROOT);
             if (typeId.equals("any") || typeId.equals("all") || typeId.equals("*")) {
                 type = NodeType.META_OR_CHAT_META;
             }
@@ -104,7 +105,7 @@ public class MetaClear extends GenericChildCommand {
         }
 
         int changed = before - target.normalData().size();
-        Message.META_CLEAR_SUCCESS.send(sender, target, type.name().toLowerCase(), context, changed);
+        Message.META_CLEAR_SUCCESS.send(sender, target, type.name().toLowerCase(Locale.ROOT), context, changed);
 
         LoggedAction.build().source(sender).target(target)
                 .description("meta", "clear", context)

common/src/main/java/me/lucko/luckperms/common/commands/generic/meta/MetaRemoveChatMeta.java

@@ -47,6 +47,7 @@ import net.luckperms.api.model.data.DataType;
 import net.luckperms.api.node.ChatMetaType;
 
 import java.util.List;
+import java.util.Locale;
 
 public class MetaRemoveChatMeta extends GenericChildCommand {
 
@@ -100,7 +101,7 @@ public class MetaRemoveChatMeta extends GenericChildCommand {
             Message.BULK_REMOVE_CHATMETA_SUCCESS.send(sender, target, this.type, priority, context);
 
             LoggedAction.build().source(sender).target(target)
-                    .description("meta" , "remove" + this.type.name().toLowerCase(), priority, "*", context)
+                    .description("meta" , "remove" + this.type.name().toLowerCase(Locale.ROOT), priority, "*", context)
                     .build().submit(plugin, sender);
 
             StorageAssistant.save(target, sender, plugin);
@@ -113,7 +114,7 @@ public class MetaRemoveChatMeta extends GenericChildCommand {
             Message.REMOVE_CHATMETA_SUCCESS.send(sender, target, this.type, meta, priority, context);
 
             LoggedAction.build().source(sender).target(target)
-                    .description("meta" , "remove" + this.type.name().toLowerCase(), priority, meta, context)
+                    .description("meta" , "remove" + this.type.name().toLowerCase(Locale.ROOT), priority, meta, context)
                     .build().submit(plugin, sender);
 
             StorageAssistant.save(target, sender, plugin);

common/src/main/java/me/lucko/luckperms/common/commands/generic/meta/MetaRemoveTempChatMeta.java

@@ -47,6 +47,7 @@ import net.luckperms.api.model.data.DataType;
 import net.luckperms.api.node.ChatMetaType;
 
 import java.util.List;
+import java.util.Locale;
 
 public class MetaRemoveTempChatMeta extends GenericChildCommand {
 
@@ -100,7 +101,7 @@ public class MetaRemoveTempChatMeta extends GenericChildCommand {
             Message.BULK_REMOVE_TEMP_CHATMETA_SUCCESS.send(sender, target, this.type, priority, context);
 
             LoggedAction.build().source(sender).target(target)
-                    .description("meta" , "removetemp" + this.type.name().toLowerCase(), priority, "*", context)
+                    .description("meta" , "removetemp" + this.type.name().toLowerCase(Locale.ROOT), priority, "*", context)
                     .build().submit(plugin, sender);
 
             StorageAssistant.save(target, sender, plugin);
@@ -113,7 +114,7 @@ public class MetaRemoveTempChatMeta extends GenericChildCommand {
             Message.REMOVE_TEMP_CHATMETA_SUCCESS.send(sender, target, this.type, meta, priority, context);
 
             LoggedAction.build().source(sender).target(target)
-                    .description("meta" , "removetemp" + this.type.name().toLowerCase(), priority, meta, context)
+                    .description("meta" , "removetemp" + this.type.name().toLowerCase(Locale.ROOT), priority, meta, context)
                     .build().submit(plugin, sender);
 
             StorageAssistant.save(target, sender, plugin);

common/src/main/java/me/lucko/luckperms/common/commands/generic/meta/MetaSetChatMeta.java

@@ -50,6 +50,7 @@ import net.luckperms.api.model.data.DataType;
 import net.luckperms.api.node.ChatMetaType;
 
 import java.util.List;
+import java.util.Locale;
 import java.util.OptionalInt;
 
 public class MetaSetChatMeta extends GenericChildCommand {
@@ -134,7 +135,7 @@ public class MetaSetChatMeta extends GenericChildCommand {
             Message.ADD_CHATMETA_SUCCESS.send(sender, target, this.type, meta, priority, context);
 
             LoggedAction.build().source(sender).target(target)
-                    .description("meta" , "set" + this.type.name().toLowerCase(), priority, meta, context)
+                    .description("meta" , "set" + this.type.name().toLowerCase(Locale.ROOT), priority, meta, context)
                     .build().submit(plugin, sender);
 
             StorageAssistant.save(target, sender, plugin);

common/src/main/java/me/lucko/luckperms/common/commands/generic/meta/MetaSetTempChatMeta.java

@@ -53,6 +53,7 @@ import net.luckperms.api.node.ChatMetaType;
 
 import java.time.Duration;
 import java.util.List;
+import java.util.Locale;
 import java.util.OptionalInt;
 
 public class MetaSetTempChatMeta extends GenericChildCommand {
@@ -146,7 +147,7 @@ public class MetaSetTempChatMeta extends GenericChildCommand {
             Message.ADD_TEMP_CHATMETA_SUCCESS.send(sender, target, this.type, meta, priority, duration, context);
 
             LoggedAction.build().source(sender).target(target)
-                    .description("meta" , "settemp" + this.type.name().toLowerCase(), priority, meta, duration, context)
+                    .description("meta" , "settemp" + this.type.name().toLowerCase(Locale.ROOT), priority, meta, duration, context)
                     .build().submit(plugin, sender);
 
             StorageAssistant.save(target, sender, plugin);

common/src/main/java/me/lucko/luckperms/common/commands/generic/parent/ParentClearTrack.java

@@ -50,6 +50,7 @@ import net.luckperms.api.model.data.DataType;
 import net.luckperms.api.node.NodeType;
 
 import java.util.List;
+import java.util.Locale;
 
 public class ParentClearTrack extends GenericChildCommand {
     public ParentClearTrack() {
@@ -63,7 +64,7 @@ public class ParentClearTrack extends GenericChildCommand {
             return;
         }
 
-        final String trackName = args.get(0).toLowerCase();
+        final String trackName = args.get(0).toLowerCase(Locale.ROOT);
         if (!DataConstraints.TRACK_NAME_TEST.test(trackName)) {
             Message.TRACK_INVALID_ENTRY.send(sender, trackName);
             return;

common/src/main/java/me/lucko/luckperms/common/commands/generic/parent/ParentSetTrack.java

@@ -50,6 +50,7 @@ import net.luckperms.api.model.data.DataType;
 import net.luckperms.api.node.NodeType;
 
 import java.util.List;
+import java.util.Locale;
 
 public class ParentSetTrack extends GenericChildCommand {
     public ParentSetTrack() {
@@ -63,7 +64,7 @@ public class ParentSetTrack extends GenericChildCommand {
             return;
         }
 
-        final String trackName = args.get(0).toLowerCase();
+        final String trackName = args.get(0).toLowerCase(Locale.ROOT);
         if (!DataConstraints.TRACK_NAME_TEST.test(trackName)) {
             Message.TRACK_INVALID_ENTRY.send(sender, trackName);
             return;

common/src/main/java/me/lucko/luckperms/common/commands/generic/parent/UserSwitchPrimaryGroup.java

@@ -51,6 +51,7 @@ import net.luckperms.api.node.Node;
 import net.luckperms.api.node.NodeEqualityPredicate;
 
 import java.util.List;
+import java.util.Locale;
 
 public class UserSwitchPrimaryGroup extends GenericChildCommand {
     public UserSwitchPrimaryGroup() {
@@ -74,9 +75,9 @@ public class UserSwitchPrimaryGroup extends GenericChildCommand {
             Message.USER_PRIMARYGROUP_WARN_OPTION.send(sender, opt);
         }
 
-        Group group = plugin.getGroupManager().getIfLoaded(args.get(0).toLowerCase());
+        Group group = plugin.getGroupManager().getIfLoaded(args.get(0).toLowerCase(Locale.ROOT));
         if (group == null) {
-            Message.DOES_NOT_EXIST.send(sender, args.get(0).toLowerCase());
+            Message.DOES_NOT_EXIST.send(sender, args.get(0).toLowerCase(Locale.ROOT));
             return;
         }
 

common/src/main/java/me/lucko/luckperms/common/commands/group/CreateGroup.java

@@ -46,6 +46,8 @@ import net.luckperms.api.actionlog.Action;
 import net.luckperms.api.event.cause.CreationCause;
 import net.luckperms.api.model.data.DataType;
 
+import java.util.Locale;
+
 public class CreateGroup extends SingleCommand {
     public CreateGroup() {
         super(CommandSpec.CREATE_GROUP, "CreateGroup", CommandPermission.CREATE_GROUP, Predicates.notInRange(1, 3));
@@ -58,7 +60,7 @@ public class CreateGroup extends SingleCommand {
             return;
         }
 
-        String groupName = args.get(0).toLowerCase();
+        String groupName = args.get(0).toLowerCase(Locale.ROOT);
         if (!DataConstraints.GROUP_NAME_TEST.test(groupName)) {
             Message.GROUP_INVALID_ENTRY.send(sender, groupName);
             return;

common/src/main/java/me/lucko/luckperms/common/commands/group/DeleteGroup.java

@@ -56,6 +56,7 @@ import net.luckperms.api.actionlog.Action;
 import net.luckperms.api.event.cause.DeletionCause;
 
 import java.util.List;
+import java.util.Locale;
 import java.util.Optional;
 
 public class DeleteGroup extends SingleCommand {
@@ -70,7 +71,7 @@ public class DeleteGroup extends SingleCommand {
             return;
         }
 
-        String groupName = args.get(0).toLowerCase();
+        String groupName = args.get(0).toLowerCase(Locale.ROOT);
 
         if (groupName.equalsIgnoreCase(GroupManager.DEFAULT_GROUP_NAME)) {
             Message.DELETE_GROUP_ERROR_DEFAULT.send(sender);

common/src/main/java/me/lucko/luckperms/common/commands/group/GroupClone.java

@@ -42,6 +42,8 @@ import me.lucko.luckperms.common.util.Predicates;
 import net.luckperms.api.event.cause.CreationCause;
 import net.luckperms.api.model.data.DataType;
 
+import java.util.Locale;
+
 public class GroupClone extends ChildCommand<Group> {
     public GroupClone() {
         super(CommandSpec.GROUP_CLONE, "clone", CommandPermission.GROUP_CLONE, Predicates.not(1));
@@ -54,7 +56,7 @@ public class GroupClone extends ChildCommand<Group> {
             return;
         }
 
-        String newGroupName = args.get(0).toLowerCase();
+        String newGroupName = args.get(0).toLowerCase(Locale.ROOT);
         if (!DataConstraints.GROUP_NAME_TEST.test(newGroupName)) {
             Message.GROUP_INVALID_ENTRY.send(sender, newGroupName);
             return;

common/src/main/java/me/lucko/luckperms/common/commands/group/GroupParentCommand.java

@@ -46,6 +46,7 @@ import me.lucko.luckperms.common.util.CaffeineFactory;
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Locale;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.locks.ReentrantLock;
 
@@ -83,7 +84,7 @@ public class GroupParentCommand extends ParentCommand<Group, String> {
         if (group != null) {
             return group.getName();
         } else {
-            return target.toLowerCase();
+            return target.toLowerCase(Locale.ROOT);
         }
     }
 

common/src/main/java/me/lucko/luckperms/common/commands/group/GroupRename.java

@@ -55,6 +55,7 @@ import net.luckperms.api.event.cause.DeletionCause;
 import net.luckperms.api.model.data.DataType;
 
 import java.util.List;
+import java.util.Locale;
 import java.util.concurrent.CompletableFuture;
 
 public class GroupRename extends ChildCommand<Group> {
@@ -69,7 +70,7 @@ public class GroupRename extends ChildCommand<Group> {
             return;
         }
 
-        String newGroupName = args.get(0).toLowerCase();
+        String newGroupName = args.get(0).toLowerCase(Locale.ROOT);
         if (!DataConstraints.GROUP_NAME_TEST.test(newGroupName)) {
             Message.GROUP_INVALID_ENTRY.send(sender, newGroupName);
             return;

common/src/main/java/me/lucko/luckperms/common/commands/log/LogGroupHistory.java

@@ -41,6 +41,7 @@ import me.lucko.luckperms.common.util.Paginated;
 import me.lucko.luckperms.common.util.Predicates;
 
 import java.util.List;
+import java.util.Locale;
 
 public class LogGroupHistory extends ChildCommand<Log> {
     private static final int ENTRIES_PER_PAGE = 10;
@@ -51,7 +52,7 @@ public class LogGroupHistory extends ChildCommand<Log> {
 
     @Override
     public void execute(LuckPermsPlugin plugin, Sender sender, Log log, ArgumentList args, String label) {
-        String group = args.get(0).toLowerCase();
+        String group = args.get(0).toLowerCase(Locale.ROOT);
         if (!DataConstraints.GROUP_NAME_TEST.test(group)) {
             Message.GROUP_INVALID_ENTRY.send(sender, group);
             return;

common/src/main/java/me/lucko/luckperms/common/commands/log/LogTrackHistory.java

@@ -41,6 +41,7 @@ import me.lucko.luckperms.common.util.Paginated;
 import me.lucko.luckperms.common.util.Predicates;
 
 import java.util.List;
+import java.util.Locale;
 
 public class LogTrackHistory extends ChildCommand<Log> {
     private static final int ENTRIES_PER_PAGE = 10;
@@ -51,7 +52,7 @@ public class LogTrackHistory extends ChildCommand<Log> {
 
     @Override
     public void execute(LuckPermsPlugin plugin, Sender sender, Log log, ArgumentList args, String label) {
-        String track = args.get(0).toLowerCase();
+        String track = args.get(0).toLowerCase(Locale.ROOT);
         if (!DataConstraints.TRACK_NAME_TEST.test(track)) {
             Message.TRACK_INVALID_ENTRY.send(sender, track);
             return;

common/src/main/java/me/lucko/luckperms/common/commands/misc/BulkUpdateCommand.java

@@ -51,6 +51,7 @@ import me.lucko.luckperms.common.sender.Sender;
 import me.lucko.luckperms.common.util.CaffeineFactory;
 import me.lucko.luckperms.common.util.Predicates;
 
+import java.util.Locale;
 import java.util.concurrent.ThreadLocalRandom;
 import java.util.concurrent.TimeUnit;
 
@@ -90,13 +91,13 @@ public class BulkUpdateCommand extends SingleCommand {
         bulkUpdateBuilder.trackStatistics(!args.remove("-s"));
 
         try {
-            bulkUpdateBuilder.dataType(DataType.valueOf(args.remove(0).toUpperCase()));
+            bulkUpdateBuilder.dataType(DataType.valueOf(args.remove(0).toUpperCase(Locale.ROOT)));
         } catch (IllegalArgumentException e) {
             Message.BULK_UPDATE_INVALID_DATA_TYPE.send(sender);
             return;
         }
 
-        String action = args.remove(0).toLowerCase();
+        String action = args.remove(0).toLowerCase(Locale.ROOT);
         switch (action) {
             case "delete":
                 bulkUpdateBuilder.action(DeleteAction.create());

common/src/main/java/me/lucko/luckperms/common/commands/misc/EditorCommand.java

@@ -45,6 +45,7 @@ import net.luckperms.api.node.Node;
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Locale;
 
 public class EditorCommand extends SingleCommand {
     public EditorCommand() {
@@ -60,7 +61,7 @@ public class EditorCommand extends SingleCommand {
         String arg0 = args.getOrDefault(0, null);
         if (arg0 != null) {
             try {
-                type = Type.valueOf(arg0.toUpperCase());
+                type = Type.valueOf(arg0.toUpperCase(Locale.ROOT));
             } catch (IllegalArgumentException e) {
                 // assume they meant it as a filter
                 filter = arg0;

common/src/main/java/me/lucko/luckperms/common/commands/misc/VerboseCommand.java

@@ -45,6 +45,7 @@ import me.lucko.luckperms.common.verbose.VerboseListener;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Locale;
 
 public class VerboseCommand extends SingleCommand {
     public VerboseCommand() {
@@ -59,7 +60,7 @@ public class VerboseCommand extends SingleCommand {
         }
 
         VerboseHandler verboseHandler = plugin.getVerboseHandler();
-        String mode = args.get(0).toLowerCase();
+        String mode = args.get(0).toLowerCase(Locale.ROOT);
 
         if (mode.equals("command") || mode.equals("cmd")) {
             if (args.size() < 3) {

common/src/main/java/me/lucko/luckperms/common/commands/track/CreateTrack.java

@@ -40,6 +40,8 @@ import net.kyori.adventure.text.Component;
 import net.luckperms.api.actionlog.Action;
 import net.luckperms.api.event.cause.CreationCause;
 
+import java.util.Locale;
+
 public class CreateTrack extends SingleCommand {
     public CreateTrack() {
         super(CommandSpec.CREATE_TRACK, "CreateTrack", CommandPermission.CREATE_TRACK, Predicates.not(1));
@@ -52,7 +54,7 @@ public class CreateTrack extends SingleCommand {
             return;
         }
 
-        String trackName = args.get(0).toLowerCase();
+        String trackName = args.get(0).toLowerCase(Locale.ROOT);
         if (!DataConstraints.TRACK_NAME_TEST.test(trackName)) {
             Message.TRACK_INVALID_ENTRY.send(sender, trackName);
             return;

common/src/main/java/me/lucko/luckperms/common/commands/track/DeleteTrack.java

@@ -44,6 +44,7 @@ import net.luckperms.api.actionlog.Action;
 import net.luckperms.api.event.cause.DeletionCause;
 
 import java.util.List;
+import java.util.Locale;
 
 public class DeleteTrack extends SingleCommand {
     public DeleteTrack() {
@@ -57,7 +58,7 @@ public class DeleteTrack extends SingleCommand {
             return;
         }
 
-        String trackName = args.get(0).toLowerCase();
+        String trackName = args.get(0).toLowerCase(Locale.ROOT);
         Track track = plugin.getStorage().loadTrack(trackName).join().orElse(null);
         if (track == null) {
             Message.TRACK_LOAD_ERROR.send(sender);

common/src/main/java/me/lucko/luckperms/common/commands/track/TrackAppend.java

@@ -45,6 +45,7 @@ import me.lucko.luckperms.common.util.Predicates;
 import net.luckperms.api.model.data.DataMutateResult;
 
 import java.util.List;
+import java.util.Locale;
 
 public class TrackAppend extends ChildCommand<Track> {
     public TrackAppend() {
@@ -58,7 +59,7 @@ public class TrackAppend extends ChildCommand<Track> {
             return;
         }
 
-        String groupName = args.get(0).toLowerCase();
+        String groupName = args.get(0).toLowerCase(Locale.ROOT);
         if (!DataConstraints.GROUP_NAME_TEST.test(groupName)) {
             sendDetailedUsage(sender, label);
             return;

common/src/main/java/me/lucko/luckperms/common/commands/track/TrackClone.java

@@ -42,6 +42,8 @@ import me.lucko.luckperms.common.util.Predicates;
 import net.kyori.adventure.text.Component;
 import net.luckperms.api.event.cause.CreationCause;
 
+import java.util.Locale;
+
 public class TrackClone extends ChildCommand<Track> {
     public TrackClone() {
         super(CommandSpec.TRACK_CLONE, "clone", CommandPermission.TRACK_CLONE, Predicates.not(1));
@@ -54,7 +56,7 @@ public class TrackClone extends ChildCommand<Track> {
             return;
         }
 
-        String newTrackName = args.get(0).toLowerCase();
+        String newTrackName = args.get(0).toLowerCase(Locale.ROOT);
         if (!DataConstraints.TRACK_NAME_TEST.test(newTrackName)) {
             Message.TRACK_INVALID_ENTRY.send(sender, newTrackName);
             return;

common/src/main/java/me/lucko/luckperms/common/commands/track/TrackInsert.java

@@ -45,6 +45,7 @@ import me.lucko.luckperms.common.util.Predicates;
 import net.luckperms.api.model.data.DataMutateResult;
 
 import java.util.List;
+import java.util.Locale;
 
 public class TrackInsert extends ChildCommand<Track> {
     public TrackInsert() {
@@ -58,7 +59,7 @@ public class TrackInsert extends ChildCommand<Track> {
             return;
         }
 
-        String groupName = args.get(0).toLowerCase();
+        String groupName = args.get(0).toLowerCase(Locale.ROOT);
         if (!DataConstraints.GROUP_NAME_TEST.test(groupName)) {
             sendDetailedUsage(sender, label);
             return;

common/src/main/java/me/lucko/luckperms/common/commands/track/TrackParentCommand.java

@@ -39,6 +39,7 @@ import me.lucko.luckperms.common.util.CaffeineFactory;
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Locale;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.locks.ReentrantLock;
 
@@ -68,7 +69,7 @@ public class TrackParentCommand extends ParentCommand<Track, String> {
 
     @Override
     protected String parseTarget(String target, LuckPermsPlugin plugin, Sender sender) {
-        return target.toLowerCase();
+        return target.toLowerCase(Locale.ROOT);
     }
 
     @Override

common/src/main/java/me/lucko/luckperms/common/commands/track/TrackRemove.java

@@ -44,6 +44,7 @@ import me.lucko.luckperms.common.util.Predicates;
 import net.luckperms.api.model.data.DataMutateResult;
 
 import java.util.List;
+import java.util.Locale;
 
 public class TrackRemove extends ChildCommand<Track> {
     public TrackRemove() {
@@ -57,7 +58,7 @@ public class TrackRemove extends ChildCommand<Track> {
             return;
         }
 
-        String groupName = args.get(0).toLowerCase();
+        String groupName = args.get(0).toLowerCase(Locale.ROOT);
         if (!DataConstraints.GROUP_NAME_TEST.test(groupName)) {
             sendDetailedUsage(sender, label);
             return;

common/src/main/java/me/lucko/luckperms/common/commands/track/TrackRename.java

@@ -43,6 +43,8 @@ import net.kyori.adventure.text.Component;
 import net.luckperms.api.event.cause.CreationCause;
 import net.luckperms.api.event.cause.DeletionCause;
 
+import java.util.Locale;
+
 public class TrackRename extends ChildCommand<Track> {
     public TrackRename() {
         super(CommandSpec.TRACK_RENAME, "rename", CommandPermission.TRACK_RENAME, Predicates.not(1));
@@ -55,7 +57,7 @@ public class TrackRename extends ChildCommand<Track> {
             return;
         }
 
-        String newTrackName = args.get(0).toLowerCase();
+        String newTrackName = args.get(0).toLowerCase(Locale.ROOT);
         if (!DataConstraints.TRACK_NAME_TEST.test(newTrackName)) {
             Message.TRACK_INVALID_ENTRY.send(sender, newTrackName);
             return;

common/src/main/java/me/lucko/luckperms/common/commands/user/UserDemote.java

@@ -47,6 +47,7 @@ import net.luckperms.api.context.MutableContextSet;
 import net.luckperms.api.track.DemotionResult;
 
 import java.util.List;
+import java.util.Locale;
 import java.util.Set;
 import java.util.function.Predicate;
 
@@ -77,7 +78,7 @@ public class UserDemote extends ChildCommand<User> {
             }
         }
 
-        final String trackName = args.get(0).toLowerCase();
+        final String trackName = args.get(0).toLowerCase(Locale.ROOT);
         if (!DataConstraints.TRACK_NAME_TEST.test(trackName)) {
             Message.TRACK_INVALID_ENTRY.send(sender, trackName);
             return;

common/src/main/java/me/lucko/luckperms/common/commands/user/UserPromote.java

@@ -47,6 +47,7 @@ import net.luckperms.api.context.MutableContextSet;
 import net.luckperms.api.track.PromotionResult;
 
 import java.util.List;
+import java.util.Locale;
 import java.util.Set;
 import java.util.function.Predicate;
 
@@ -77,7 +78,7 @@ public class UserPromote extends ChildCommand<User> {
             }
         }
 
-        final String trackName = args.get(0).toLowerCase();
+        final String trackName = args.get(0).toLowerCase(Locale.ROOT);
         if (!DataConstraints.TRACK_NAME_TEST.test(trackName)) {
             Message.TRACK_INVALID_ENTRY.send(sender, trackName);
             return;

common/src/main/java/me/lucko/luckperms/common/config/ConfigKeys.java

@@ -59,6 +59,7 @@ import java.util.ArrayList;
 import java.util.EnumMap;
 import java.util.EnumSet;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Set;
@@ -86,9 +87,9 @@ public final class ConfigKeys {
      * The name of the server
      */
     public static final ConfigKey<String> SERVER = key(c -> {
-        String server = c.getString("server", "global").toLowerCase();
+        String server = c.getString("server", "global").toLowerCase(Locale.ROOT);
         if (server.equals("load-from-system-property")) {
-            server = System.getProperty("luckperms.server", "global").toLowerCase();
+            server = System.getProperty("luckperms.server", "global").toLowerCase(Locale.ROOT);
         }
         return server;
     });
@@ -191,7 +192,7 @@ public final class ConfigKeys {
      */
     public static final ConfigKey<TemporaryNodeMergeStrategy> TEMPORARY_ADD_BEHAVIOUR = key(c -> {
         String value = c.getString("temporary-add-behaviour", "deny");
-        switch (value.toLowerCase()) {
+        switch (value.toLowerCase(Locale.ROOT)) {
             case "accumulate":
                 return TemporaryNodeMergeStrategy.ADD_NEW_DURATION_TO_EXISTING;
             case "replace":
@@ -205,7 +206,7 @@ public final class ConfigKeys {
      * How primary groups should be calculated.
      */
     public static final ConfigKey<String> PRIMARY_GROUP_CALCULATION_METHOD = notReloadable(key(c -> {
-        String option = c.getString("primary-group-calculation", "stored").toLowerCase();
+        String option = c.getString("primary-group-calculation", "stored").toLowerCase(Locale.ROOT);
         if (!option.equals("stored") && !option.equals("parents-by-weight") && !option.equals("all-parents-by-weight")) {
             option = "stored";
         }
@@ -318,7 +319,7 @@ public final class ConfigKeys {
      */
     public static final ConfigKey<TraversalAlgorithm> INHERITANCE_TRAVERSAL_ALGORITHM = key(c -> {
         String value = c.getString("inheritance-traversal-algorithm", "depth-first-pre-order");
-        switch (value.toLowerCase()) {
+        switch (value.toLowerCase(Locale.ROOT)) {
             case "breadth-first":
                 return TraversalAlgorithm.BREADTH_FIRST;
             case "depth-first-post-order":
@@ -355,7 +356,7 @@ public final class ConfigKeys {
      */
     public static final ConfigKey<Map<String, Integer>> GROUP_WEIGHTS = key(c -> {
         return c.getStringMap("group-weight", ImmutableMap.of()).entrySet().stream().collect(ImmutableCollectors.toMap(
-                e -> e.getKey().toLowerCase(),
+                e -> e.getKey().toLowerCase(Locale.ROOT),
                 e -> {
                     try {
                         return Integer.parseInt(e.getValue());
@@ -378,7 +379,7 @@ public final class ConfigKeys {
         String middleSpacer = l.getString("meta-formatting.prefix.middle-spacer", " ");
         String endSpacer = l.getString("meta-formatting.prefix.end-spacer", "");
         DuplicateRemovalFunction duplicateRemovalFunction;
-        switch (l.getString("meta-formatting.prefix.duplicates", "").toLowerCase()) {
+        switch (l.getString("meta-formatting.prefix.duplicates", "").toLowerCase(Locale.ROOT)) {
             case "first-only":
                 duplicateRemovalFunction = DuplicateRemovalFunction.FIRST_ONLY;
                 break;
@@ -405,7 +406,7 @@ public final class ConfigKeys {
         String middleSpacer = l.getString("meta-formatting.suffix.middle-spacer", " ");
         String endSpacer = l.getString("meta-formatting.suffix.end-spacer", "");
         DuplicateRemovalFunction duplicateRemovalFunction;
-        switch (l.getString("meta-formatting.prefix.duplicates", "").toLowerCase()) {
+        switch (l.getString("meta-formatting.prefix.duplicates", "").toLowerCase(Locale.ROOT)) {
             case "first-only":
                 duplicateRemovalFunction = DuplicateRemovalFunction.FIRST_ONLY;
                 break;
@@ -493,7 +494,7 @@ public final class ConfigKeys {
     public static final ConfigKey<String> VAULT_SERVER = key(c -> {
         // default to true for backwards compatibility
         if (USE_VAULT_SERVER.get(c)) {
-            return c.getString("vault-server", "global").toLowerCase();
+            return c.getString("vault-server", "global").toLowerCase(Locale.ROOT);
         } else {
             return SERVER.get(c);
         }
@@ -520,8 +521,8 @@ public final class ConfigKeys {
     public static final ConfigKey<WorldNameRewriter> WORLD_REWRITES = key(c -> {
         return WorldNameRewriter.of(c.getStringMap("world-rewrite", ImmutableMap.of()).entrySet().stream()
                 .collect(ImmutableCollectors.toMap(
-                        e -> e.getKey().toLowerCase(),
+                        e -> e.getKey().toLowerCase(Locale.ROOT),
-                        e -> e.getValue().toLowerCase()
+                        e -> e.getValue().toLowerCase(Locale.ROOT)
                 )));
     });
 

common/src/main/java/me/lucko/luckperms/common/config/generic/key/ConfigKeyFactory.java

@@ -29,6 +29,7 @@ import com.google.common.collect.ImmutableMap;
 
 import me.lucko.luckperms.common.config.generic.adapter.ConfigurationAdapter;
 
+import java.util.Locale;
 import java.util.Map;
 import java.util.function.Function;
 
@@ -36,7 +37,7 @@ public interface ConfigKeyFactory<T> {
 
     ConfigKeyFactory<Boolean> BOOLEAN = ConfigurationAdapter::getBoolean;
     ConfigKeyFactory<String> STRING = ConfigurationAdapter::getString;
-    ConfigKeyFactory<String> LOWERCASE_STRING = (adapter, path, def) -> adapter.getString(path, def).toLowerCase();
+    ConfigKeyFactory<String> LOWERCASE_STRING = (adapter, path, def) -> adapter.getString(path, def).toLowerCase(Locale.ROOT);
     ConfigKeyFactory<Map<String, String>> STRING_MAP = (config, path, def) -> ImmutableMap.copyOf(config.getStringMap(path, ImmutableMap.of()));
 
     static <T> SimpleConfigKey<T> key(Function<ConfigurationAdapter, T> function) {

common/src/main/java/me/lucko/luckperms/common/context/WorldNameRewriter.java

@@ -32,6 +32,7 @@ import net.luckperms.api.context.ContextConsumer;
 import net.luckperms.api.context.DefaultContextKeys;
 
 import java.util.HashSet;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Set;
 
@@ -69,7 +70,7 @@ public interface WorldNameRewriter {
         @Override
         public void rewriteAndSubmit(String worldName, ContextConsumer consumer) {
             Set<String> seen = new HashSet<>();
-            worldName = worldName.toLowerCase();
+            worldName = worldName.toLowerCase(Locale.ROOT);
 
             while (Context.isValidValue(worldName) && seen.add(worldName)) {
                 consumer.accept(DefaultContextKeys.WORLD_KEY, worldName);

common/src/main/java/me/lucko/luckperms/common/context/contextset/AbstractContextSet.java

@@ -39,6 +39,7 @@ import org.checkerframework.checker.nullness.qual.NonNull;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Iterator;
+import java.util.Locale;
 import java.util.Objects;
 import java.util.Set;
 import java.util.Spliterator;
@@ -127,7 +128,7 @@ public abstract class AbstractContextSet implements ContextSet {
         if (!Context.isValidKey(key)) {
             throw new IllegalArgumentException("key is (effectively) empty");
         }
-        return key.toLowerCase();
+        return key.toLowerCase(Locale.ROOT);
     }
 
     static String sanitizeValue(String value) {
@@ -135,7 +136,7 @@ public abstract class AbstractContextSet implements ContextSet {
         if (!Context.isValidValue(value)) {
             throw new IllegalArgumentException("value is (effectively) empty");
         }
-        return value.toLowerCase();
+        return value.toLowerCase(Locale.ROOT);
     }
 
     public static boolean isGlobalServerWorldEntry(String key, String value) {

common/src/main/java/me/lucko/luckperms/common/dependencies/Dependency.java

@@ -35,6 +35,7 @@ import java.security.NoSuchAlgorithmException;
 import java.util.Arrays;
 import java.util.Base64;
 import java.util.List;
+import java.util.Locale;
 
 /**
  * The dependencies used by LuckPerms.
@@ -314,7 +315,7 @@ public enum Dependency {
     }
 
     public String getFileName(String classifier) {
-        String name = name().toLowerCase().replace('_', '-');
+        String name = name().toLowerCase(Locale.ROOT).replace('_', '-');
         String extra = classifier == null || classifier.isEmpty()
                 ? ""
                 : "-" + classifier;

common/src/main/java/me/lucko/luckperms/common/messaging/MessagingFactory.java

@@ -42,6 +42,8 @@ import net.luckperms.api.messenger.MessengerProvider;
 
 import org.checkerframework.checker.nullness.qual.NonNull;
 
+import java.util.Locale;
+
 public class MessagingFactory<P extends LuckPermsPlugin> {
     private final P plugin;
 
@@ -82,7 +84,7 @@ public class MessagingFactory<P extends LuckPermsPlugin> {
             return null;
         }
 
-        this.plugin.getLogger().info("Loading messaging service... [" + messagingType.toUpperCase() + "]");
+        this.plugin.getLogger().info("Loading messaging service... [" + messagingType.toUpperCase(Locale.ROOT) + "]");
 
         InternalMessagingService service = getServiceFor(messagingType);
         if (service != null) {

common/src/main/java/me/lucko/luckperms/common/metastacking/StandardStackElements.java

@@ -39,6 +39,7 @@ import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 import java.util.List;
+import java.util.Locale;
 import java.util.Objects;
 
 /**
@@ -48,7 +49,7 @@ public final class StandardStackElements {
     private StandardStackElements() {}
 
     public static MetaStackElement parseFromString(LuckPermsPlugin plugin, String s) {
-        s = s.toLowerCase();
+        s = s.toLowerCase(Locale.ROOT);
 
         // static
         if (s.equals("highest")) return HIGHEST;

common/src/main/java/me/lucko/luckperms/common/model/Group.java

@@ -40,6 +40,7 @@ import net.luckperms.api.query.QueryOptions;
 
 import org.checkerframework.checker.nullness.qual.NonNull;
 
+import java.util.Locale;
 import java.util.Optional;
 import java.util.OptionalInt;
 
@@ -68,7 +69,7 @@ public class Group extends PermissionHolder {
 
     public Group(String name, LuckPermsPlugin plugin) {
         super(plugin);
-        this.name = name.toLowerCase();
+        this.name = name.toLowerCase(Locale.ROOT);
 
         this.cachedData = new GroupCachedDataManager(this);
         getPlugin().getEventDispatcher().dispatchGroupCacheLoad(this, this.cachedData);

common/src/main/java/me/lucko/luckperms/common/model/HolderType.java

@@ -25,12 +25,14 @@
 
 package me.lucko.luckperms.common.model;
 
+import java.util.Locale;
+
 public enum HolderType {
     USER,
     GROUP;
 
     @Override
     public String toString() {
-        return name().toLowerCase();
+        return name().toLowerCase(Locale.ROOT);
     }
 }

common/src/main/java/me/lucko/luckperms/common/model/PermissionHolder.java

@@ -63,6 +63,7 @@ import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Comparator;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.OptionalInt;
 import java.util.SortedSet;
@@ -363,7 +364,7 @@ public abstract class PermissionHolder {
     private static void processExportedPermissions(Map<String, Boolean> accumulator, List<Node> entries, boolean convertToLowercase, boolean resolveShorthand) {
         for (Node node : entries) {
             if (convertToLowercase) {
-                accumulator.putIfAbsent(node.getKey().toLowerCase(), node.getValue());
+                accumulator.putIfAbsent(node.getKey().toLowerCase(Locale.ROOT), node.getValue());
             } else {
                 accumulator.putIfAbsent(node.getKey(), node.getValue());
             }
@@ -374,7 +375,7 @@ public abstract class PermissionHolder {
                 Collection<String> shorthand = node.resolveShorthand();
                 for (String s : shorthand) {
                     if (convertToLowercase) {
-                        accumulator.putIfAbsent(s.toLowerCase(), node.getValue());
+                        accumulator.putIfAbsent(s.toLowerCase(Locale.ROOT), node.getValue());
                     } else {
                         accumulator.putIfAbsent(s, node.getValue());
                     }

common/src/main/java/me/lucko/luckperms/common/model/PrimaryGroupHolder.java

@@ -32,6 +32,7 @@ import net.luckperms.api.node.types.InheritanceNode;
 import net.luckperms.api.query.QueryOptions;
 
 import java.util.LinkedHashSet;
+import java.util.Locale;
 import java.util.Objects;
 import java.util.Optional;
 import java.util.Set;
@@ -90,7 +91,7 @@ public interface PrimaryGroupHolder {
             if (value == null || value.isEmpty()) {
                 this.value = null;
             } else {
-                this.value = value.toLowerCase();
+                this.value = value.toLowerCase(Locale.ROOT);
             }
         }
     }

common/src/main/java/me/lucko/luckperms/common/model/WeightCache.java

@@ -34,6 +34,7 @@ import net.luckperms.api.node.types.WeightNode;
 
 import org.checkerframework.checker.nullness.qual.NonNull;
 
+import java.util.Locale;
 import java.util.Map;
 import java.util.OptionalInt;
 
@@ -62,7 +63,7 @@ public class WeightCache extends Cache<OptionalInt> {
 
         if (!seen) {
             Map<String, Integer> configWeights = this.group.getPlugin().getConfiguration().get(ConfigKeys.GROUP_WEIGHTS);
-            Integer value = configWeights.get(this.group.getObjectName().toLowerCase());
+            Integer value = configWeights.get(this.group.getObjectName().toLowerCase(Locale.ROOT));
             if (value != null) {
                 seen = true;
                 weight = value;

common/src/main/java/me/lucko/luckperms/common/model/manager/group/AbstractGroupManager.java

@@ -28,6 +28,7 @@ package me.lucko.luckperms.common.model.manager.group;
 import me.lucko.luckperms.common.model.Group;
 import me.lucko.luckperms.common.model.manager.AbstractManager;
 
+import java.util.Locale;
 import java.util.Optional;
 
 public abstract class AbstractGroupManager<T extends Group> extends AbstractManager<String, Group, T> implements GroupManager<T> {
@@ -61,7 +62,7 @@ public abstract class AbstractGroupManager<T extends Group> extends AbstractMana
 
     @Override
     protected String sanitizeIdentifier(String s) {
-        return s.toLowerCase();
+        return s.toLowerCase(Locale.ROOT);
     }
 
     @Override

common/src/main/java/me/lucko/luckperms/common/model/manager/track/AbstractTrackManager.java

@@ -28,10 +28,12 @@ package me.lucko.luckperms.common.model.manager.track;
 import me.lucko.luckperms.common.model.Track;
 import me.lucko.luckperms.common.model.manager.AbstractManager;
 
+import java.util.Locale;
+
 public abstract class AbstractTrackManager<T extends Track> extends AbstractManager<String, Track, T> implements TrackManager<T> {
 
     @Override
     protected String sanitizeIdentifier(String s) {
-        return s.toLowerCase();
+        return s.toLowerCase(Locale.ROOT);
     }
 }

common/src/main/java/me/lucko/luckperms/common/node/types/DisplayName.java

@@ -35,6 +35,7 @@ import net.luckperms.api.node.types.DisplayNameNode;
 import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
+import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
 
@@ -72,7 +73,7 @@ public class DisplayName extends AbstractNode<DisplayNameNode, DisplayNameNode.B
     }
 
     public static @Nullable Builder parse(String key) {
-        if (!key.toLowerCase().startsWith(NODE_MARKER)) {
+        if (!key.toLowerCase(Locale.ROOT).startsWith(NODE_MARKER)) {
             return null;
         }
 

common/src/main/java/me/lucko/luckperms/common/node/types/Inheritance.java

@@ -36,6 +36,7 @@ import net.luckperms.api.node.types.InheritanceNode;
 import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
+import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
 
@@ -44,7 +45,7 @@ public class Inheritance extends AbstractNode<InheritanceNode, InheritanceNode.B
     private static final String NODE_MARKER = NODE_KEY + ".";
 
     public static String key(String groupName) {
-        return NODE_MARKER + groupName.toLowerCase();
+        return NODE_MARKER + groupName.toLowerCase(Locale.ROOT);
     }
 
     public static Builder builder() {
@@ -59,7 +60,7 @@ public class Inheritance extends AbstractNode<InheritanceNode, InheritanceNode.B
 
     public Inheritance(String groupName, boolean value, long expireAt, ImmutableContextSet contexts, Map<NodeMetadataKey<?>, Object> metadata) {
         super(key(groupName), value, expireAt, contexts, metadata);
-        this.groupName = groupName.toLowerCase();
+        this.groupName = groupName.toLowerCase(Locale.ROOT);
     }
 
     @Override
@@ -73,7 +74,7 @@ public class Inheritance extends AbstractNode<InheritanceNode, InheritanceNode.B
     }
 
     public static @Nullable Builder parse(String key) {
-        key = key.toLowerCase();
+        key = key.toLowerCase(Locale.ROOT);
         if (!key.startsWith(NODE_MARKER)) {
             return null;
         }

common/src/main/java/me/lucko/luckperms/common/node/types/Meta.java

@@ -37,6 +37,7 @@ import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 import java.util.Iterator;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
 
@@ -45,7 +46,7 @@ public class Meta extends AbstractNode<MetaNode, MetaNode.Builder> implements Me
     private static final String NODE_MARKER = NODE_KEY + ".";
 
     public static String key(String key, String value) {
-        return NODE_MARKER + Delimiters.escapeCharacters(key).toLowerCase() + AbstractNode.NODE_SEPARATOR + Delimiters.escapeCharacters(value);
+        return NODE_MARKER + Delimiters.escapeCharacters(key).toLowerCase(Locale.ROOT) + AbstractNode.NODE_SEPARATOR + Delimiters.escapeCharacters(value);
     }
 
     public static Builder builder() {
@@ -61,7 +62,7 @@ public class Meta extends AbstractNode<MetaNode, MetaNode.Builder> implements Me
 
     public Meta(String metaKey, String metaValue, boolean value, long expireAt, ImmutableContextSet contexts, Map<NodeMetadataKey<?>, Object> metadata) {
         super(key(metaKey, metaValue), value, expireAt, contexts, metadata);
-        this.metaKey = metaKey.toLowerCase();
+        this.metaKey = metaKey.toLowerCase(Locale.ROOT);
         this.metaValue = metaValue;
     }
 
@@ -81,7 +82,7 @@ public class Meta extends AbstractNode<MetaNode, MetaNode.Builder> implements Me
     }
 
     public static @Nullable Builder parse(String key) {
-        if (!key.toLowerCase().startsWith(NODE_MARKER)) {
+        if (!key.toLowerCase(Locale.ROOT).startsWith(NODE_MARKER)) {
             return null;
         }
 

common/src/main/java/me/lucko/luckperms/common/node/types/Prefix.java

@@ -38,6 +38,7 @@ import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 import java.util.Iterator;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
 
@@ -87,7 +88,7 @@ public class Prefix extends AbstractNode<PrefixNode, PrefixNode.Builder> impleme
     }
 
     public static @Nullable Builder parse(String key) {
-        if (!key.toLowerCase().startsWith(NODE_MARKER)) {
+        if (!key.toLowerCase(Locale.ROOT).startsWith(NODE_MARKER)) {
             return null;
         }
 

common/src/main/java/me/lucko/luckperms/common/node/types/Suffix.java

@@ -38,6 +38,7 @@ import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 import java.util.Iterator;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
 
@@ -87,7 +88,7 @@ public class Suffix extends AbstractNode<SuffixNode, SuffixNode.Builder> impleme
     }
 
     public static @Nullable Builder parse(String key) {
-        if (!key.toLowerCase().startsWith(NODE_MARKER)) {
+        if (!key.toLowerCase(Locale.ROOT).startsWith(NODE_MARKER)) {
             return null;
         }
 

common/src/main/java/me/lucko/luckperms/common/node/types/Weight.java

@@ -35,6 +35,7 @@ import net.luckperms.api.node.types.WeightNode;
 import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
+import java.util.Locale;
 import java.util.Map;
 
 public class Weight extends AbstractNode<WeightNode, WeightNode.Builder> implements WeightNode {
@@ -71,7 +72,7 @@ public class Weight extends AbstractNode<WeightNode, WeightNode.Builder> impleme
     }
 
     public static @Nullable Builder parse(String key) {
-        if (!key.toLowerCase().startsWith(NODE_MARKER)) {
+        if (!key.toLowerCase(Locale.ROOT).startsWith(NODE_MARKER)) {
             return null;
         }
 

common/src/main/java/me/lucko/luckperms/common/node/utils/NodeJsonSerializer.java

@@ -38,6 +38,7 @@ import net.luckperms.api.node.NodeBuilder;
 import java.time.Instant;
 import java.util.Collection;
 import java.util.HashSet;
+import java.util.Locale;
 import java.util.Set;
 
 public class NodeJsonSerializer {
@@ -51,7 +52,7 @@ public class NodeJsonSerializer {
         for (Node node : nodes) {
             JsonObject attributes = new JsonObject();
 
-            attributes.addProperty("type", node.getType().name().toLowerCase());
+            attributes.addProperty("type", node.getType().name().toLowerCase(Locale.ROOT));
             attributes.addProperty("key", node.getKey());
             attributes.addProperty("value", node.getValue());
 

common/src/main/java/me/lucko/luckperms/common/plugin/AbstractLuckPermsPlugin.java

@@ -71,6 +71,7 @@ import java.time.Instant;
 import java.time.LocalDate;
 import java.time.Month;
 import java.util.EnumSet;
+import java.util.Locale;
 import java.util.Optional;
 import java.util.Set;
 import java.util.UUID;
@@ -336,7 +337,7 @@ public abstract class AbstractLuckPermsPlugin implements LuckPermsPlugin {
     @Override
     public Optional<UUID> lookupUniqueId(String username) {
         // get a result from the DB cache
-        UUID uniqueId = getStorage().getPlayerUniqueId(username.toLowerCase()).join();
+        UUID uniqueId = getStorage().getPlayerUniqueId(username.toLowerCase(Locale.ROOT)).join();
 
         // fire the event
         uniqueId = getEventDispatcher().dispatchUniqueIdLookup(username, uniqueId);

common/src/main/java/me/lucko/luckperms/common/storage/Storage.java

@@ -49,6 +49,7 @@ import net.luckperms.api.node.Node;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Optional;
 import java.util.Set;
@@ -171,7 +172,7 @@ public class Storage {
 
     public CompletableFuture<Group> createAndLoadGroup(String name, CreationCause cause) {
         return future(() -> {
-            Group group = this.implementation.createAndLoadGroup(name.toLowerCase());
+            Group group = this.implementation.createAndLoadGroup(name.toLowerCase(Locale.ROOT));
             if (group != null) {
                 this.plugin.getEventDispatcher().dispatchGroupCreate(group, cause);
             }
@@ -181,7 +182,7 @@ public class Storage {
 
     public CompletableFuture<Optional<Group>> loadGroup(String name) {
         return future(() -> {
-            Optional<Group> group = this.implementation.loadGroup(name.toLowerCase());
+            Optional<Group> group = this.implementation.loadGroup(name.toLowerCase(Locale.ROOT));
             if (group.isPresent()) {
                 this.plugin.getEventDispatcher().dispatchGroupLoad(group.get());
             }
@@ -217,7 +218,7 @@ public class Storage {
 
     public CompletableFuture<Track> createAndLoadTrack(String name, CreationCause cause) {
         return future(() -> {
-            Track track = this.implementation.createAndLoadTrack(name.toLowerCase());
+            Track track = this.implementation.createAndLoadTrack(name.toLowerCase(Locale.ROOT));
             if (track != null) {
                 this.plugin.getEventDispatcher().dispatchTrackCreate(track, cause);
             }
@@ -227,7 +228,7 @@ public class Storage {
 
     public CompletableFuture<Optional<Track>> loadTrack(String name) {
         return future(() -> {
-            Optional<Track> track = this.implementation.loadTrack(name.toLowerCase());
+            Optional<Track> track = this.implementation.loadTrack(name.toLowerCase(Locale.ROOT));
             if (track.isPresent()) {
                 this.plugin.getEventDispatcher().dispatchTrackLoad(track.get());
             }

common/src/main/java/me/lucko/luckperms/common/storage/implementation/file/FileUuidCache.java

@@ -46,6 +46,7 @@ import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.HashSet;
 import java.util.Iterator;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Set;
 import java.util.UUID;
@@ -200,11 +201,11 @@ public class FileUuidCache {
             // existing might be null
             if (!value.equalsIgnoreCase(existing)) {
                 if (existing != null) {
-                    this.reverse.remove(existing.toLowerCase(), key);
+                    this.reverse.remove(existing.toLowerCase(Locale.ROOT), key);
                 }
             }
 
-            this.reverse.put(value.toLowerCase(), key);
+            this.reverse.put(value.toLowerCase(Locale.ROOT), key);
             return existing;
         }
 
@@ -213,7 +214,7 @@ public class FileUuidCache {
             UUID key = (UUID) k;
             String username = super.remove(key);
             if (username != null) {
-                this.reverse.remove(username.toLowerCase(), key);
+                this.reverse.remove(username.toLowerCase(Locale.ROOT), key);
             }
             return username;
         }
@@ -223,7 +224,7 @@ public class FileUuidCache {
         }
 
         public Set<UUID> lookupUuid(String name) {
-            return this.reverse.get(name.toLowerCase());
+            return this.reverse.get(name.toLowerCase(Locale.ROOT));
         }
     }
 

common/src/main/java/me/lucko/luckperms/common/storage/implementation/mongodb/MongoStorage.java

@@ -75,6 +75,7 @@ import java.util.Collections;
 import java.util.HashSet;
 import java.util.LinkedHashMap;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Optional;
 import java.util.Set;
@@ -521,7 +522,7 @@ public class MongoStorage implements StorageImplementation {
 
     @Override
     public PlayerSaveResult savePlayerData(UUID uniqueId, String username) {
-        username = username.toLowerCase();
+        username = username.toLowerCase(Locale.ROOT);
         MongoCollection<Document> c = this.database.getCollection(this.prefix + "uuid");
 
         // find any existing mapping
@@ -560,7 +561,7 @@ public class MongoStorage implements StorageImplementation {
     @Override
     public UUID getPlayerUniqueId(String username) {
         MongoCollection<Document> c = this.database.getCollection(this.prefix + "uuid");
-        Document doc = c.find(new Document("name", username.toLowerCase())).first();
+        Document doc = c.find(new Document("name", username.toLowerCase(Locale.ROOT))).first();
         if (doc != null) {
             return getDocumentId(doc);
         }

common/src/main/java/me/lucko/luckperms/common/storage/implementation/split/SplitStorage.java

@@ -46,6 +46,7 @@ import net.luckperms.api.node.Node;
 
 import java.util.LinkedHashMap;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Optional;
 import java.util.Set;
@@ -114,7 +115,7 @@ public class SplitStorage implements StorageImplementation {
         meta.put(
                 Component.translatable("luckperms.command.info.storage.meta.split-types-key"),
                 Message.formatStringList(this.types.entrySet().stream()
-                        .map(e -> e.getKey().toString().toLowerCase() + "->" + e.getValue().getName().toLowerCase())
+                        .map(e -> e.getKey().toString().toLowerCase(Locale.ROOT) + "->" + e.getValue().getName().toLowerCase(Locale.ROOT))
                         .collect(Collectors.toList()))
         );
         for (StorageImplementation backing : this.implementations.values()) {

common/src/main/java/me/lucko/luckperms/common/storage/implementation/sql/SqlStorage.java

@@ -72,6 +72,7 @@ import java.util.Collection;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Optional;
 import java.util.Set;
@@ -173,7 +174,7 @@ public class SqlStorage implements StorageImplementation {
     private void applySchema() throws IOException, SQLException {
         List<String> statements;
 
-        String schemaFileName = "me/lucko/luckperms/schema/" + this.connectionFactory.getImplementationName().toLowerCase() + ".sql";
+        String schemaFileName = "me/lucko/luckperms/schema/" + this.connectionFactory.getImplementationName().toLowerCase(Locale.ROOT) + ".sql";
         try (InputStream is = this.plugin.getBootstrap().getResourceStream(schemaFileName)) {
             if (is == null) {
                 throw new IOException("Couldn't locate schema file for " + this.connectionFactory.getImplementationName());
@@ -375,7 +376,7 @@ public class SqlStorage implements StorageImplementation {
             updateUserPermissions(c, user.getUniqueId(), changes.getAdded(), changes.getRemoved());
             insertPlayerData(c, user.getUniqueId(), new SqlPlayerData(
                     user.getPrimaryGroup().getStoredValue().orElse(GroupManager.DEFAULT_GROUP_NAME),
-                    user.getUsername().orElse("null").toLowerCase()
+                    user.getUsername().orElse("null").toLowerCase(Locale.ROOT)
             ));
         }
     }
@@ -605,7 +606,7 @@ public class SqlStorage implements StorageImplementation {
 
     @Override
     public PlayerSaveResult savePlayerData(UUID uniqueId, String username) throws SQLException {
-        username = username.toLowerCase();
+        username = username.toLowerCase(Locale.ROOT);
 
         // find any existing mapping
         String oldUsername = getPlayerName(uniqueId);
@@ -672,7 +673,7 @@ public class SqlStorage implements StorageImplementation {
 
     @Override
     public UUID getPlayerUniqueId(String username) throws SQLException {
-        username = username.toLowerCase();
+        username = username.toLowerCase(Locale.ROOT);
         try (Connection c = this.connectionFactory.getConnection()) {
             try (PreparedStatement ps = c.prepareStatement(this.statementProcessor.apply(PLAYER_SELECT_UUID_BY_USERNAME))) {
                 ps.setString(1, username);
@@ -907,7 +908,7 @@ public class SqlStorage implements StorageImplementation {
         try (PreparedStatement ps = c.prepareStatement(this.statementProcessor.apply(GROUP_SELECT_ALL))) {
             try (ResultSet rs = ps.executeQuery()) {
                 while (rs.next()) {
-                    groups.add(rs.getString("name").toLowerCase());
+                    groups.add(rs.getString("name").toLowerCase(Locale.ROOT));
                 }
             }
         }
@@ -992,7 +993,7 @@ public class SqlStorage implements StorageImplementation {
         try (PreparedStatement ps = c.prepareStatement(this.statementProcessor.apply(TRACK_SELECT_ALL))) {
             try (ResultSet rs = ps.executeQuery()) {
                 while (rs.next()) {
-                    tracks.add(rs.getString("name").toLowerCase());
+                    tracks.add(rs.getString("name").toLowerCase(Locale.ROOT));
                 }
             }
         }

common/src/main/java/me/lucko/luckperms/common/treeview/PermissionRegistry.java

@@ -32,6 +32,7 @@ import me.lucko.luckperms.common.plugin.scheduler.SchedulerTask;
 import me.lucko.luckperms.common.util.ImmutableCollectors;
 
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Queue;
 import java.util.concurrent.ConcurrentLinkedQueue;
@@ -93,7 +94,7 @@ public class PermissionRegistry implements AutoCloseable {
     }
 
     private void doInsert(String permission) {
-        permission = permission.toLowerCase();
+        permission = permission.toLowerCase(Locale.ROOT);
 
         // split the permission up into parts
         Iterable<String> parts = DOT_SPLIT.split(permission);

common/src/main/java/me/lucko/luckperms/common/treeview/TreeView.java

@@ -46,6 +46,7 @@ import java.nio.charset.StandardCharsets;
 import java.text.SimpleDateFormat;
 import java.util.Date;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Optional;
 import java.util.zip.GZIPOutputStream;
@@ -160,7 +161,7 @@ public class TreeView {
             checks = new JObject();
             for (Map.Entry<Integer, String> node : this.view.getNodeEndings()) {
                 String permission = prefix + node.getValue();
-                checks.add(permission, checker.checkPermission(permission, PermissionCheckEvent.Origin.INTERNAL).result().name().toLowerCase());
+                checks.add(permission, checker.checkPermission(permission, PermissionCheckEvent.Origin.INTERNAL).result().name().toLowerCase(Locale.ROOT));
             }
         } else {
             checks = null;

common/src/main/java/me/lucko/luckperms/common/util/DurationFormatter.java

@@ -34,6 +34,7 @@ import net.kyori.adventure.text.serializer.plain.PlainComponentSerializer;
 
 import java.time.Duration;
 import java.time.temporal.ChronoUnit;
+import java.util.Locale;
 
 /**
  * Formats durations to a readable form
@@ -115,7 +116,7 @@ public class DurationFormatter {
 
     private TranslatableComponent formatPart(long amount, ChronoUnit unit) {
         String format = this.concise ? "short" : amount == 1 ? "singular" : "plural";
-        String translationKey = "luckperms.duration.unit." + unit.name().toLowerCase() + "." + format;
+        String translationKey = "luckperms.duration.unit." + unit.name().toLowerCase(Locale.ROOT) + "." + format;
         return Component.translatable(translationKey, Component.text(amount));
     }
 

common/src/main/java/me/lucko/luckperms/common/util/EnumNamer.java

@@ -26,6 +26,7 @@
 package me.lucko.luckperms.common.util;
 
 import java.util.Collections;
+import java.util.Locale;
 import java.util.Map;
 import java.util.function.Function;
 
@@ -35,7 +36,7 @@ import java.util.function.Function;
  * @param <E> the enum type
  */
 public class EnumNamer<E extends Enum<E>> {
-    public static final Function<Enum<?>, String> LOWER_CASE_NAME = value -> value.name().toLowerCase();
+    public static final Function<Enum<?>, String> LOWER_CASE_NAME = value -> value.name().toLowerCase(Locale.ROOT);
 
     private final String[] names;
     private final Function<? super E, String> namingFunction;

common/src/main/java/me/lucko/luckperms/common/verbose/event/MetaCheckEvent.java

@@ -30,6 +30,8 @@ import me.lucko.luckperms.common.verbose.VerboseCheckTarget;
 
 import net.luckperms.api.query.QueryOptions;
 
+import java.util.Locale;
+
 public class MetaCheckEvent extends VerboseEvent {
 
     /**
@@ -71,14 +73,14 @@ public class MetaCheckEvent extends VerboseEvent {
         object.add("type", "meta")
                 .add("key", this.key)
                 .add("result", this.result)
-                .add("origin", this.origin.name().toLowerCase());
+                .add("origin", this.origin.name().toLowerCase(Locale.ROOT));
     }
 
     @Override
     public boolean eval(String variable) {
         return variable.equals("meta") ||
                 getCheckTarget().describe().equalsIgnoreCase(variable) ||
-                getKey().toLowerCase().startsWith(variable.toLowerCase()) ||
+                getKey().toLowerCase(Locale.ROOT).startsWith(variable.toLowerCase(Locale.ROOT)) ||
                 getResult().equalsIgnoreCase(variable);
     }
 

common/src/main/java/me/lucko/luckperms/common/verbose/event/PermissionCheckEvent.java

@@ -31,6 +31,8 @@ import me.lucko.luckperms.common.verbose.VerboseCheckTarget;
 
 import net.luckperms.api.query.QueryOptions;
 
+import java.util.Locale;
+
 public class PermissionCheckEvent extends VerboseEvent {
 
     /**
@@ -72,7 +74,7 @@ public class PermissionCheckEvent extends VerboseEvent {
         object.add("type", "permission");
         object.add("permission", this.permission);
 
-        object.add("result", this.result.result().name().toLowerCase());
+        object.add("result", this.result.result().name().toLowerCase(Locale.ROOT));
         if (this.result.processorClass() != null || this.result.cause() != null) {
             JObject resultInfo = new JObject();
             if (this.result.processorClass() != null) {
@@ -84,14 +86,14 @@ public class PermissionCheckEvent extends VerboseEvent {
             object.add("resultInfo", resultInfo);
         }
 
-        object.add("origin", this.origin.name().toLowerCase());
+        object.add("origin", this.origin.name().toLowerCase(Locale.ROOT));
     }
 
     @Override
     public boolean eval(String variable) {
         return variable.equals("permission") ||
                 getCheckTarget().describe().equalsIgnoreCase(variable) ||
-                getPermission().toLowerCase().startsWith(variable.toLowerCase()) ||
+                getPermission().toLowerCase(Locale.ROOT).startsWith(variable.toLowerCase(Locale.ROOT)) ||
                 getResult().result().name().equalsIgnoreCase(variable);
     }
 

common/src/main/java/me/lucko/luckperms/common/verbose/event/VerboseEvent.java

@@ -37,6 +37,7 @@ import net.luckperms.api.context.Context;
 import net.luckperms.api.query.QueryMode;
 import net.luckperms.api.query.QueryOptions;
 
+import java.util.Locale;
 import java.util.Objects;
 import java.util.UUID;
 
@@ -113,7 +114,7 @@ public abstract class VerboseEvent implements VariableEvaluator {
                             }
                         })
                 )
-                .add("queryMode", this.checkQueryOptions.mode().name().toLowerCase())
+                .add("queryMode", this.checkQueryOptions.mode().name().toLowerCase(Locale.ROOT))
                 .consume(obj -> {
                     if (this.checkQueryOptions.mode() == QueryMode.CONTEXTUAL) {
                         obj.add("context", new JArray()

common/src/test/java/me/lucko/luckperms/common/util/EnumNamerTest.java

@@ -29,6 +29,8 @@ import com.google.common.collect.ImmutableMap;
 
 import org.junit.jupiter.api.Test;
 
+import java.util.Locale;
+
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
 public class EnumNamerTest {
@@ -38,7 +40,7 @@ public class EnumNamerTest {
         EnumNamer<TestEnum> namer = new EnumNamer<>(
                 TestEnum.class,
                 ImmutableMap.of(TestEnum.THING, "hi"),
-                v -> v.name().toLowerCase().replace('_', '-')
+                v -> v.name().toLowerCase(Locale.ROOT).replace('_', '-')
         );
 
         assertEquals("test", namer.name(TestEnum.TEST));

nukkit/src/main/java/me/lucko/luckperms/nukkit/context/NukkitPlayerCalculator.java

@@ -47,6 +47,7 @@ import cn.nukkit.event.entity.EntityLevelChangeEvent;
 import cn.nukkit.event.player.PlayerGameModeChangeEvent;
 import cn.nukkit.level.Level;
 
+import java.util.Locale;
 import java.util.Set;
 
 public class NukkitPlayerCalculator implements ContextCalculator<Player>, Listener {
@@ -111,7 +112,7 @@ public class NukkitPlayerCalculator implements ContextCalculator<Player>, Listen
             case Player.CREATIVE: return "creative";
             case Player.ADVENTURE: return "adventure";
             case Player.SPECTATOR: return "spectator";
-            default: return Server.getGamemodeString(mode, true).toLowerCase();
+            default: return Server.getGamemodeString(mode, true).toLowerCase(Locale.ROOT);
         }
     }
 

nukkit/src/main/java/me/lucko/luckperms/nukkit/inject/PermissionDefault.java

@@ -30,6 +30,7 @@ import org.checkerframework.checker.nullness.qual.Nullable;
 import cn.nukkit.permission.Permission;
 
 import java.util.HashMap;
+import java.util.Locale;
 import java.util.Map;
 
 /**
@@ -84,7 +85,7 @@ public enum PermissionDefault {
      * @return Specified value, or null if not found
      */
     public static @Nullable PermissionDefault getByName(String name) {
-        return LOOKUP.get(name.toLowerCase().replaceAll("[^a-z!]", ""));
+        return LOOKUP.get(name.toLowerCase(Locale.ROOT).replaceAll("[^a-z!]", ""));
     }
 
     public static @Nullable PermissionDefault fromPermission(@Nullable Permission permission) {

nukkit/src/main/java/me/lucko/luckperms/nukkit/inject/permissible/LuckPermsPermissionAttachment.java

@@ -47,6 +47,7 @@ import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Set;
@@ -238,7 +239,7 @@ public class LuckPermsPermissionAttachment extends PermissionAttachment {
         Objects.requireNonNull(name, "name is null");
         Preconditions.checkArgument(!name.isEmpty(), "name is empty");
 
-        String permission = name.toLowerCase();
+        String permission = name.toLowerCase(Locale.ROOT);
 
         Boolean previous = this.perms.put(permission, value);
         if (previous != null && previous == value) {
@@ -275,7 +276,7 @@ public class LuckPermsPermissionAttachment extends PermissionAttachment {
         Objects.requireNonNull(name, "name is null");
         Preconditions.checkArgument(!name.isEmpty(), "name is empty");
 
-        String permission = name.toLowerCase();
+        String permission = name.toLowerCase(Locale.ROOT);
 
         Boolean previous = this.perms.remove(permission);
         if (previous == null) {

nukkit/src/main/java/me/lucko/luckperms/nukkit/inject/server/LuckPermsDefaultsMap.java

@@ -40,6 +40,7 @@ import cn.nukkit.plugin.PluginManager;
 
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.Locale;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 
@@ -159,7 +160,7 @@ public final class LuckPermsDefaultsMap {
         protected @NonNull Map<String, Boolean> supply() {
             Map<String, Boolean> builder = new HashMap<>();
             for (Permission perm : LuckPermsDefaultsMap.this.get(this.op).values()) {
-                String name = perm.getName().toLowerCase();
+                String name = perm.getName().toLowerCase(Locale.ROOT);
                 builder.put(name, true);
                 for (Map.Entry<String, Boolean> child : LuckPermsDefaultsMap.this.plugin.getPermissionMap().getChildPermissions(name, true).entrySet()) {
                     builder.putIfAbsent(child.getKey(), child.getValue());

nukkit/src/main/java/me/lucko/luckperms/nukkit/inject/server/LuckPermsPermissionMap.java

@@ -41,6 +41,7 @@ import cn.nukkit.plugin.PluginManager;
 import java.lang.reflect.Field;
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
 import java.util.concurrent.ConcurrentHashMap;
@@ -180,7 +181,7 @@ public final class LuckPermsPermissionMap extends ForwardingMap<String, Permissi
                 continue;
             }
 
-            String key = e.getKey().toLowerCase();
+            String key = e.getKey().toLowerCase(Locale.ROOT);
 
             if (accumulator.containsKey(key)) {
                 continue; // Prevent infinite loops

nukkit/src/main/java/me/lucko/luckperms/nukkit/listeners/NukkitPlatformListener.java

@@ -37,6 +37,7 @@ import cn.nukkit.event.player.PlayerCommandPreprocessEvent;
 import cn.nukkit.event.server.RemoteServerCommandEvent;
 import cn.nukkit.event.server.ServerCommandEvent;
 
+import java.util.Locale;
 import java.util.regex.Pattern;
 
 public class NukkitPlatformListener implements Listener {
@@ -50,17 +51,17 @@ public class NukkitPlatformListener implements Listener {
 
     @EventHandler(ignoreCancelled = true)
     public void onPlayerCommand(PlayerCommandPreprocessEvent e) {
-        handleCommand(e.getPlayer(), e.getMessage().toLowerCase(), e);
+        handleCommand(e.getPlayer(), e.getMessage().toLowerCase(Locale.ROOT), e);
     }
 
     @EventHandler(ignoreCancelled = true)
     public void onServerCommand(ServerCommandEvent e) {
-        handleCommand(e.getSender(), e.getCommand().toLowerCase(), e);
+        handleCommand(e.getSender(), e.getCommand().toLowerCase(Locale.ROOT), e);
     }
 
     @EventHandler(ignoreCancelled = true)
     public void onRemoteServerCommand(RemoteServerCommandEvent e) {
-        handleCommand(e.getSender(), e.getCommand().toLowerCase(), e);
+        handleCommand(e.getSender(), e.getCommand().toLowerCase(Locale.ROOT), e);
     }
 
     private void handleCommand(CommandSender sender, String cmdLine, Cancellable event) {

sponge/sponge-service-api7/src/main/java/me/lucko/luckperms/sponge/service/proxy/api7/PermissionServiceProxy.java

@@ -44,6 +44,7 @@ import org.spongepowered.api.service.permission.SubjectCollection;
 import org.spongepowered.api.service.permission.SubjectReference;
 
 import java.util.Collection;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Optional;
@@ -85,12 +86,12 @@ public final class PermissionServiceProxy implements PermissionService, ProxiedS
 
     @Override
     public @NonNull Optional<SubjectCollection> getCollection(String s) {
-        return Optional.ofNullable(this.handle.getLoadedCollections().get(s.toLowerCase())).map(LPSubjectCollection::sponge);
+        return Optional.ofNullable(this.handle.getLoadedCollections().get(s.toLowerCase(Locale.ROOT))).map(LPSubjectCollection::sponge);
     }
 
     @Override
     public CompletableFuture<Boolean> hasCollection(String s) {
-        return CompletableFuture.completedFuture(this.handle.getLoadedCollections().containsKey(s.toLowerCase()));
+        return CompletableFuture.completedFuture(this.handle.getLoadedCollections().containsKey(s.toLowerCase(Locale.ROOT)));
     }
 
     @Override
@@ -113,7 +114,7 @@ public final class PermissionServiceProxy implements PermissionService, ProxiedS
         Objects.requireNonNull(subjectIdentifier, "subjectIdentifier");
 
         // test the identifiers
-        String collection = collectionIdentifier.toLowerCase();
+        String collection = collectionIdentifier.toLowerCase(Locale.ROOT);
         if (collection.equals("user") && !this.handle.getUserSubjects().getIdentifierValidityPredicate().test(subjectIdentifier)) {
             throw new IllegalArgumentException("Subject identifier '" + subjectIdentifier + "' does not pass the validity predicate for the user subject collection");
         } else if (collection.equals("group") && !this.handle.getGroupSubjects().getIdentifierValidityPredicate().test(subjectIdentifier)) {