Reduce technical debt

* Reduce duplicate code
* Use more specific functional interfaces where available
* Fix some potential NPEs
* Remove some unnecessary/nonfunctional code
* Merge inventory listeners - no longer need to keep separate due to event availability
* Removed TODO items that probably won't ever be implemented. Good ideas, too drastic changes or too much work to maintain.

api/src/main/java/com/lishid/openinv/util/InventoryAccess.java

@@ -18,6 +18,7 @@ package com.lishid.openinv.util;
 
 import com.lishid.openinv.internal.IInventoryAccess;
 import com.lishid.openinv.internal.ISpecialEnderChest;
+import com.lishid.openinv.internal.ISpecialInventory;
 import com.lishid.openinv.internal.ISpecialPlayerInventory;
 import java.lang.reflect.Field;
 import java.lang.reflect.Method;
@@ -33,9 +34,8 @@ public class InventoryAccess implements IInventoryAccess {
 
     static {
         String packageName = Bukkit.getServer().getClass().getPackage().getName();
-        String version = packageName.substring(packageName.lastIndexOf('.') + 1);
         try {
-            craftInventory = Class.forName("org.bukkit.craftbukkit." + version + ".inventory.CraftInventory");
+            craftInventory = Class.forName(packageName + ".inventory.CraftInventory");
         } catch (ClassNotFoundException ignored) {}
         try {
             getInventory = craftInventory.getDeclaredMethod("getInventory");
@@ -47,62 +47,42 @@ public class InventoryAccess implements IInventoryAccess {
     }
 
     public static boolean isPlayerInventory(@NotNull Inventory inventory) {
-        if (craftInventory.isAssignableFrom(inventory.getClass())) {
+        return getPlayerInventory(inventory) != null;
-            try {
-                return getInventory.invoke(inventory) instanceof ISpecialPlayerInventory;
-            } catch (ReflectiveOperationException ignored) {}
-        }
-        return grabFieldOfTypeFromObject(ISpecialPlayerInventory.class, inventory) != null;
     }
 
-    public static ISpecialPlayerInventory getPlayerInventory(@NotNull Inventory inventory) {
+    public static @Nullable ISpecialPlayerInventory getPlayerInventory(@NotNull Inventory inventory) {
-        Object inv = null;
+        return getSpecialInventory(ISpecialPlayerInventory.class, inventory);
-        if (craftInventory.isAssignableFrom(inventory.getClass())) {
-            try {
-                inv = getInventory.invoke(inventory);
-            } catch (ReflectiveOperationException ignored) {}
-        }
-
-        if (inv == null) {
-            inv = grabFieldOfTypeFromObject(ISpecialPlayerInventory.class, inventory);
-        }
-
-        if (inv instanceof ISpecialPlayerInventory) {
-            return (ISpecialPlayerInventory) inv;
-        }
-
-        return null;
     }
 
     public static boolean isEnderChest(@NotNull Inventory inventory) {
-        if (craftInventory.isAssignableFrom(inventory.getClass())) {
+        return getEnderChest(inventory) != null;
-            try {
-                return getInventory.invoke(inventory) instanceof ISpecialEnderChest;
-            } catch (ReflectiveOperationException ignored) {}
-        }
-        return grabFieldOfTypeFromObject(ISpecialEnderChest.class, inventory) != null;
     }
 
-    public static ISpecialEnderChest getEnderChest(@NotNull Inventory inventory) {
+    public static @Nullable ISpecialEnderChest getEnderChest(@NotNull Inventory inventory) {
-        Object inv = null;
+        return getSpecialInventory(ISpecialEnderChest.class, inventory);
-        if (craftInventory.isAssignableFrom(inventory.getClass())) {
+    }
+
+    private static <T extends ISpecialInventory> @Nullable T getSpecialInventory(@NotNull Class<T> expected, @NotNull Inventory inventory) {
+        Object inv;
+        if (craftInventory != null && getInventory != null && craftInventory.isAssignableFrom(inventory.getClass())) {
             try {
                 inv = getInventory.invoke(inventory);
+                if (expected.isInstance(inv)) {
+                    return expected.cast(inv);
+                }
             } catch (ReflectiveOperationException ignored) {}
         }
 
-        if (inv == null) {
+        inv = grabFieldOfTypeFromObject(ISpecialPlayerInventory.class, inventory);
-            inv = grabFieldOfTypeFromObject(ISpecialEnderChest.class, inventory);
-        }
 
-        if (inv instanceof ISpecialEnderChest) {
+        if (expected.isInstance(inv)) {
-            return (ISpecialEnderChest) inv;
+            return expected.cast(inv);
         }
 
         return null;
     }
 
-    private static <T> T grabFieldOfTypeFromObject(final Class<T> type, final Object object) {
+    private static <T> @Nullable T grabFieldOfTypeFromObject(final Class<T> type, final Object object) {
         // Use reflection to find the IInventory
         Class<?> clazz = object.getClass();
         T result = null;
@@ -142,4 +122,5 @@ public class InventoryAccess implements IInventoryAccess {
     public boolean isSpecialPlayerInventory(@NotNull Inventory inventory) {
         return isPlayerInventory(inventory);
     }
+
 }

plugin/src/main/java/com/lishid/openinv/OpenInv.java

@@ -27,9 +27,7 @@ import com.lishid.openinv.internal.IAnySilentContainer;
 import com.lishid.openinv.internal.ISpecialEnderChest;
 import com.lishid.openinv.internal.ISpecialInventory;
 import com.lishid.openinv.internal.ISpecialPlayerInventory;
-import com.lishid.openinv.listeners.InventoryClickListener;
+import com.lishid.openinv.listeners.InventoryListener;
-import com.lishid.openinv.listeners.InventoryCloseListener;
-import com.lishid.openinv.listeners.InventoryDragListener;
 import com.lishid.openinv.listeners.PlayerListener;
 import com.lishid.openinv.listeners.PluginListener;
 import com.lishid.openinv.util.Cache;
@@ -105,7 +103,6 @@ public class OpenInv extends JavaPlugin implements IOpenInv {
                 if (!OpenInv.this.disableSaving() && !value.isOnline()) {
                     value.saveData();
                 }
-                return true;
             });
 
     private InternalAccessor accessor;
@@ -127,6 +124,7 @@ public class OpenInv extends JavaPlugin implements IOpenInv {
 
         if (this.inventories.containsKey(key)) {
             Iterator<HumanEntity> iterator = this.inventories.get(key).getBukkitInventory().getViewers().iterator();
+            //noinspection WhileLoopReplaceableByForEach
             while (iterator.hasNext()) {
                 HumanEntity human = iterator.next();
                 // If player has permission or is in the same world, allow continued access
@@ -140,6 +138,7 @@ public class OpenInv extends JavaPlugin implements IOpenInv {
 
         if (this.enderChests.containsKey(key)) {
             Iterator<HumanEntity> iterator = this.enderChests.get(key).getBukkitInventory().getViewers().iterator();
+            //noinspection WhileLoopReplaceableByForEach
             while (iterator.hasNext()) {
                 HumanEntity human = iterator.next();
                 if (Permissions.CROSSWORLD.hasPermission(human) || human.getWorld().equals(player.getWorld())) {
@@ -222,22 +221,18 @@ public class OpenInv extends JavaPlugin implements IOpenInv {
         return this.accessor != null && this.accessor.isSupported();
     }
 
-    @Nullable
     @Override
-    public Player loadPlayer(@NotNull final OfflinePlayer offline) {
+    public @Nullable Player loadPlayer(@NotNull final OfflinePlayer offline) {
 
         String key = this.getPlayerID(offline);
         if (this.playerCache.containsKey(key)) {
             return this.playerCache.get(key);
         }
 
-        // TODO: wrap Player to ensure all methods can safely be called offline
+        Player player = offline.getPlayer();
-        Player loaded;
+        if (player != null) {
-
+            this.playerCache.put(key, player);
-        if (offline.isOnline()) {
+            return player;
-            loaded = offline.getPlayer();
-            this.playerCache.put(key, loaded);
-            return loaded;
         }
 
         if (!this.isSupportedVersion()) {
@@ -251,33 +246,18 @@ public class OpenInv extends JavaPlugin implements IOpenInv {
         Future<Player> future = Bukkit.getScheduler().callSyncMethod(this,
                 () -> OpenInv.this.accessor.getPlayerDataManager().loadPlayer(offline));
 
-        int ticks = 0;
-        while (!future.isDone() && !future.isCancelled() && ticks < 10) {
-            ++ticks;
         try {
-                Thread.sleep(50L);
+            player = future.get();
-            } catch (InterruptedException e) {
-                e.printStackTrace();
-                return null;
-            }
-        }
-
-        if (!future.isDone() || future.isCancelled()) {
-            return null;
-        }
-
-        try {
-            loaded = future.get();
         } catch (InterruptedException | ExecutionException e) {
             e.printStackTrace();
             return null;
         }
 
-        if (loaded != null) {
+        if (player != null) {
-            this.playerCache.put(key, loaded);
+            this.playerCache.put(key, player);
         }
 
-        return loaded;
+        return player;
     }
 
     @Override
@@ -317,8 +297,7 @@ public class OpenInv extends JavaPlugin implements IOpenInv {
         return this.languageManager.getValue(key, getLocale(sender), replacements);
     }
 
-    @Nullable
+    private @Nullable String getLocale(@NotNull CommandSender sender) {
-    private String getLocale(@NotNull CommandSender sender) {
         if (sender instanceof Player) {
             return this.accessor.getPlayerDataManager().getLocale((Player) sender);
         } else {
@@ -369,10 +348,7 @@ public class OpenInv extends JavaPlugin implements IOpenInv {
             // Register listeners
             pm.registerEvents(new PlayerListener(this), this);
             pm.registerEvents(new PluginListener(this), this);
-            pm.registerEvents(new InventoryClickListener(), this);
+            pm.registerEvents(new InventoryListener(this), this);
-            pm.registerEvents(new InventoryCloseListener(this), this);
-            // Bukkit will handle missing events for us, attempt to register InventoryDragEvent without a version check
-            pm.registerEvents(new InventoryDragListener(), this);
 
             // Register commands to their executors
             OpenInvCommand openInv = new OpenInvCommand(this);

plugin/src/main/java/com/lishid/openinv/commands/ContainerSettingCommand.java

@@ -21,7 +21,7 @@ import com.lishid.openinv.util.TabCompleter;
 import java.util.Collections;
 import java.util.List;
 import java.util.function.BiConsumer;
-import java.util.function.Function;
+import java.util.function.Predicate;
 import org.bukkit.OfflinePlayer;
 import org.bukkit.command.Command;
 import org.bukkit.command.CommandSender;
@@ -46,7 +46,7 @@ public class ContainerSettingCommand implements TabExecutor {
 
         Player player = (Player) sender;
         boolean any = command.getName().startsWith("any");
-        Function<Player, Boolean> getSetting = any ? plugin::getPlayerAnyChestStatus : plugin::getPlayerSilentChestStatus;
+        Predicate<Player> getSetting = any ? plugin::getPlayerAnyChestStatus : plugin::getPlayerSilentChestStatus;
         BiConsumer<OfflinePlayer, Boolean> setSetting = any ? plugin::setPlayerAnyChestStatus : plugin::setPlayerSilentChestStatus;
 
         if (args.length > 0) {
@@ -62,12 +62,12 @@ public class ContainerSettingCommand implements TabExecutor {
             }
 
         } else {
-            setSetting.accept(player, !getSetting.apply(player));
+            setSetting.accept(player, !getSetting.test(player));
         }
 
-        String onOff = plugin.getLocalizedMessage(player, getSetting.apply(player) ? "messages.info.on" : "messages.info.off");
+        String onOff = plugin.getLocalizedMessage(player, getSetting.test(player) ? "messages.info.on" : "messages.info.off");
         if (onOff == null) {
-            onOff = String.valueOf(getSetting.apply(player));
+            onOff = String.valueOf(getSetting.test(player));
         }
 
         plugin.sendMessage(sender, "messages.info.settingState","%setting%", any ? "AnyContainer" : "SilentContainer", "%state%", onOff);

plugin/src/main/java/com/lishid/openinv/commands/SearchEnchantCommand.java

@@ -31,6 +31,7 @@ import org.bukkit.inventory.Inventory;
 import org.bukkit.inventory.ItemStack;
 import org.bukkit.inventory.meta.ItemMeta;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 /**
  * Command adding the ability to search online players' inventories for enchantments of a specific
@@ -124,8 +125,9 @@ public class SearchEnchantCommand implements TabExecutor {
         return true;
     }
 
-    private boolean containsEnchantment(Inventory inventory, Enchantment enchant, int minLevel) {
+    private boolean containsEnchantment(Inventory inventory, @Nullable Enchantment enchant, int minLevel) {
         for (ItemStack item : inventory.getContents()) {
+            //noinspection ConstantConditions // Spigot improperly annotated, should be ItemStack @NotNull []
             if (item == null || item.getType() == Material.AIR) {
                 continue;
             }

plugin/src/main/java/com/lishid/openinv/listeners/InventoryClickListener.java

@@ -1,40 +0,0 @@
-/*
- * Copyright (C) 2011-2020 lishid. All rights reserved.
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>.
- */
-
-package com.lishid.openinv.listeners;
-
-import com.lishid.openinv.util.InventoryAccess;
-import com.lishid.openinv.util.Permissions;
-import org.bukkit.entity.HumanEntity;
-import org.bukkit.event.EventHandler;
-import org.bukkit.event.EventPriority;
-import org.bukkit.event.Listener;
-import org.bukkit.event.inventory.InventoryClickEvent;
-import org.bukkit.inventory.Inventory;
-
-public class InventoryClickListener implements Listener {
-
-    @EventHandler(priority = EventPriority.NORMAL, ignoreCancelled = true)
-    public void onInventoryClick(InventoryClickEvent event) {
-        HumanEntity entity = event.getWhoClicked();
-        Inventory inventory = event.getInventory();
-        if (InventoryAccess.isPlayerInventory(inventory) && !Permissions.EDITINV.hasPermission(entity)
-                || InventoryAccess.isEnderChest(inventory) && !Permissions.EDITENDER.hasPermission(entity)) {
-            event.setCancelled(true);
-        }
-    }
-
-}

plugin/src/main/java/com/lishid/openinv/listeners/InventoryCloseListener.java

@@ -1,46 +0,0 @@
-/*
- * Copyright (C) 2011-2020 lishid. All rights reserved.
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>.
- */
-
-package com.lishid.openinv.listeners;
-
-import com.lishid.openinv.IOpenInv;
-import org.bukkit.entity.Player;
-import org.bukkit.event.EventHandler;
-import org.bukkit.event.Listener;
-import org.bukkit.event.inventory.InventoryCloseEvent;
-
-public class InventoryCloseListener implements Listener {
-
-    private final IOpenInv plugin;
-
-    public InventoryCloseListener(final IOpenInv plugin) {
-        this.plugin = plugin;
-    }
-
-    @EventHandler
-    public void onInventoryClose(final InventoryCloseEvent event) {
-        if (!(event.getPlayer() instanceof Player)) {
-            return;
-        }
-
-        Player player = (Player) event.getPlayer();
-
-        if (this.plugin.getPlayerSilentChestStatus(player)) {
-            this.plugin.getAnySilentContainer().deactivateContainer(player);
-        }
-    }
-
-}

plugin/src/main/java/com/lishid/openinv/listeners/InventoryListener.java

@@ -16,24 +16,57 @@
 
 package com.lishid.openinv.listeners;
 
+import com.lishid.openinv.IOpenInv;
 import com.lishid.openinv.util.InventoryAccess;
 import com.lishid.openinv.util.Permissions;
 import org.bukkit.entity.HumanEntity;
+import org.bukkit.entity.Player;
 import org.bukkit.event.EventHandler;
 import org.bukkit.event.EventPriority;
 import org.bukkit.event.Listener;
+import org.bukkit.event.inventory.InventoryClickEvent;
+import org.bukkit.event.inventory.InventoryCloseEvent;
 import org.bukkit.event.inventory.InventoryDragEvent;
+import org.bukkit.event.inventory.InventoryInteractEvent;
 import org.bukkit.inventory.Inventory;
 
 /**
- * Listener for InventoryDragEvents to prevent unpermitted modification of special inventories.
+ * Listener for inventory-related events to prevent modification of inventories where not allowed.
  *
  * @author Jikoo
  */
-public class InventoryDragListener implements Listener {
+public class InventoryListener implements Listener {
+
+    private final IOpenInv plugin;
+
+    public InventoryListener(final IOpenInv plugin) {
+        this.plugin = plugin;
+    }
+
+    @EventHandler
+    public void onInventoryClose(final InventoryCloseEvent event) {
+        if (!(event.getPlayer() instanceof Player)) {
+            return;
+        }
+
+        Player player = (Player) event.getPlayer();
+
+        if (this.plugin.getPlayerSilentChestStatus(player)) {
+            this.plugin.getAnySilentContainer().deactivateContainer(player);
+        }
+    }
+
+    @EventHandler(priority = EventPriority.NORMAL, ignoreCancelled = true)
+    public void onInventoryClick(InventoryClickEvent event) {
+        onInventoryInteract(event);
+    }
 
     @EventHandler(priority = EventPriority.NORMAL, ignoreCancelled = true)
     public void onInventoryDrag(InventoryDragEvent event) {
+        onInventoryInteract(event);
+    }
+
+    private void onInventoryInteract(InventoryInteractEvent event) {
         HumanEntity entity = event.getWhoClicked();
         Inventory inventory = event.getInventory();
         if (InventoryAccess.isPlayerInventory(inventory) && !Permissions.EDITINV.hasPermission(entity)

plugin/src/main/java/com/lishid/openinv/util/Cache.java

@@ -24,7 +24,8 @@ import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
-import java.util.function.Function;
+import java.util.function.Consumer;
+import java.util.function.Predicate;
 
 /**
  * A minimal thread-safe time-based cache implementation backed by a HashMap and TreeMultimap.
@@ -36,16 +37,17 @@ public class Cache<K, V> {
     private final Map<K, V> internal;
     private final Multimap<Long, K> expiry;
     private final long retention;
-    private final Function<V, Boolean> inUseCheck, postRemoval;
+    private final Predicate<V> inUseCheck;
+    private final Consumer<V> postRemoval;
 
     /**
      * Constructs a Cache with the specified retention duration, in use function, and post-removal function.
      *
      * @param retention duration after which keys are automatically invalidated if not in use
-     * @param inUseCheck Function used to check if a key is considered in use
+     * @param inUseCheck Predicate used to check if a key is considered in use
-     * @param postRemoval Function used to perform any operations required when a key is invalidated
+     * @param postRemoval Consumer used to perform any operations required when a key is invalidated
      */
-    public Cache(final long retention, final Function<V, Boolean> inUseCheck, final Function<V, Boolean> postRemoval) {
+    public Cache(final long retention, final Predicate<V> inUseCheck, final Consumer<V> postRemoval) {
         this.internal = new HashMap<>();
 
         this.expiry = TreeMultimap.create(Long::compareTo, (k1, k2) -> Objects.equals(k1, k2) ? 0 : 1);
@@ -136,7 +138,7 @@ public class Cache<K, V> {
     public void invalidateAll() {
         synchronized (this.internal) {
             for (V value : this.internal.values()) {
-                this.postRemoval.apply(value);
+                this.postRemoval.accept(value);
             }
             this.expiry.clear();
             this.internal.clear();
@@ -161,7 +163,7 @@ public class Cache<K, V> {
 
                 iterator.remove();
 
-                if (this.inUseCheck.apply(this.internal.get(entry.getValue()))) {
+                if (this.inUseCheck.test(this.internal.get(entry.getValue()))) {
                     inUse.add(entry.getValue());
                     continue;
                 }
@@ -172,7 +174,7 @@ public class Cache<K, V> {
                     continue;
                 }
 
-                this.postRemoval.apply(value);
+                this.postRemoval.accept(value);
             }
 
             long nextExpiry = now + this.retention;

plugin/src/main/java/com/lishid/openinv/util/ConfigUpdater.java

@@ -24,7 +24,6 @@ import java.util.Map;
 import java.util.Set;
 import org.bukkit.OfflinePlayer;
 import org.bukkit.configuration.ConfigurationSection;
-import org.bukkit.scheduler.BukkitRunnable;
 
 public class ConfigUpdater {
 
@@ -36,7 +35,8 @@ public class ConfigUpdater {
 
     public void checkForUpdates() {
         final int version = plugin.getConfig().getInt("config-version", 1);
-        if (version >= plugin.getConfig().getDefaults().getInt("config-version")) {
+        ConfigurationSection defaults = plugin.getConfig().getDefaults();
+        if (defaults == null || version >= defaults.getInt("config-version")) {
             return;
         }
 
@@ -50,9 +50,7 @@ public class ConfigUpdater {
             plugin.getLogger().warning("Could not back up config.yml before updating!");
         }
 
-        new BukkitRunnable() {
+        plugin.getServer().getScheduler().runTaskAsynchronously(plugin, () -> {
-            @Override
-            public void run() {
             if (version < 2) {
                 updateConfig1To2();
             }
@@ -63,32 +61,23 @@ public class ConfigUpdater {
                 updateConfig3To4();
             }
 
-                new BukkitRunnable() {
+            plugin.getServer().getScheduler().runTask(plugin, () -> {
-                    @Override
-                    public void run() {
                 plugin.saveConfig();
                 plugin.getLogger().info("Configuration update complete!");
-                    }
+            });
-                }.runTaskLater(plugin, 1L); // Run on 1 tick delay; on older versions Bukkit's scheduler is not guaranteed FIFO
+        });
-            }
-        }.runTaskAsynchronously(plugin);
     }
 
     private void updateConfig3To4() {
-        new BukkitRunnable() {
+        plugin.getServer().getScheduler().runTask(plugin, () -> {
-            @Override
-            public void run() {
             plugin.getConfig().set("notify", null);
             plugin.getConfig().set("settings.locale", "en_US");
             plugin.getConfig().set("config-version", 4);
-            }
+        });
-        }.runTask(plugin);
     }
 
     private void updateConfig2To3() {
-        new BukkitRunnable() {
+        plugin.getServer().getScheduler().runTask(plugin, () -> {
-            @Override
-            public void run() {
             plugin.getConfig().set("config-version", 3);
             plugin.getConfig().set("items.open-inv", null);
             plugin.getConfig().set("ItemOpenInv", null);
@@ -96,14 +85,11 @@ public class ConfigUpdater {
             plugin.getConfig().set("settings.disable-saving",
                     plugin.getConfig().getBoolean("DisableSaving", false));
             plugin.getConfig().set("DisableSaving", null);
-            }
+        });
-        }.runTask(plugin);
     }
 
     private void updateConfig1To2() {
-        new BukkitRunnable() {
+        plugin.getServer().getScheduler().runTask(plugin, () -> {
-            @Override
-            public void run() {
             // Get the old config settings
             boolean notifySilentChest = plugin.getConfig().getBoolean("NotifySilentChest", true);
             boolean notifyAnyChest = plugin.getConfig().getBoolean("NotifyAnyChest", true);
@@ -113,24 +99,23 @@ public class ConfigUpdater {
             plugin.getConfig().set("config-version", 2);
             plugin.getConfig().set("notify.any-chest", notifyAnyChest);
             plugin.getConfig().set("notify.silent-chest", notifySilentChest);
-            }
+        });
-        }.runTask(plugin);
 
         updateToggles("AnyChest", "toggles.any-chest");
         updateToggles("SilentChest", "toggles.silent-chest");
     }
 
     private void updateToggles(final String sectionName, final String newSectionName) {
+        ConfigurationSection section = plugin.getConfig().getConfigurationSection(sectionName);
         // Ensure section exists
-        if (!plugin.getConfig().isConfigurationSection(sectionName)) {
+        if (section == null) {
             return;
         }
 
-        ConfigurationSection section = plugin.getConfig().getConfigurationSection(sectionName);
         Set<String> keys = section.getKeys(false);
 
         // Ensure section has content
-        if (keys == null || keys.isEmpty()) {
+        if (keys.isEmpty()) {
             return;
         }
 
@@ -143,25 +128,20 @@ public class ConfigUpdater {
             }
         }
 
-        new BukkitRunnable() {
+        plugin.getServer().getScheduler().runTask(plugin, () -> {
-            @Override
-            public void run() {
             // Wipe old ConfigurationSection
             plugin.getConfig().set(sectionName, null);
 
             // Prepare new ConfigurationSection
-                ConfigurationSection newSection;
+            ConfigurationSection newSection = plugin.getConfig().getConfigurationSection(newSectionName);
-                if (plugin.getConfig().isConfigurationSection(newSectionName)) {
+            if (newSection == null) {
-                    newSection = plugin.getConfig().getConfigurationSection(newSectionName);
-                } else {
                 newSection = plugin.getConfig().createSection(newSectionName);
             }
             // Set new values
             for (Map.Entry<String, Boolean> entry : toggles.entrySet()) {
                 newSection.set(entry.getKey(), entry.getValue());
             }
-            }
+        });
-        }.runTask(plugin);
     }
 
 }

plugin/src/main/java/com/lishid/openinv/util/InternalAccessor.java

@@ -40,7 +40,6 @@ public class InternalAccessor {
         this.version = packageName.substring(packageName.lastIndexOf('.') + 1);
 
         try {
-            // TODO: implement support for CraftMagicNumbers#getMappingsVersion
             Class.forName("com.lishid.openinv.internal." + this.version + ".SpecialPlayerInventory");
             Class.forName("com.lishid.openinv.internal." + this.version + ".SpecialEnderChest");
             this.playerDataManager = this.createObject(IPlayerDataManager.class, "PlayerDataManager");

plugin/src/main/java/com/lishid/openinv/util/LanguageManager.java

@@ -41,7 +41,7 @@ public class LanguageManager {
 
 	private final OpenInv plugin;
 	private final String defaultLocale;
-	private Map<String, YamlConfiguration> locales;
+	private final Map<String, YamlConfiguration> locales;
 
 	public LanguageManager(@NotNull OpenInv plugin, @NotNull String defaultLocale) {
 		this.plugin = plugin;