Make variables final if they can be.

src/main/java/world/bentobox/bentobox/api/addons/Addon.java

@@ -40,7 +40,7 @@ public abstract class Addon {
     private FileConfiguration config;
     private File dataFolder;
     private File file;
-    private Map<String, AddonRequestHandler> requestHandlers = new HashMap<>();
+    private final Map<String, AddonRequestHandler> requestHandlers = new HashMap<>();
 
     protected Addon() {
         state = State.DISABLED;

src/main/java/world/bentobox/bentobox/api/addons/AddonClassLoader.java

@@ -30,8 +30,8 @@
 public class AddonClassLoader extends URLClassLoader {
 
     private final Map<String, Class<?>> classes = new HashMap<>();
-    private Addon addon;
-    private AddonsManager loader;
+    private final Addon addon;
+    private final AddonsManager loader;
 
     public AddonClassLoader(AddonsManager addonsManager, YamlConfiguration data, File jarFile, ClassLoader parent)
             throws InvalidAddonInheritException,

src/main/java/world/bentobox/bentobox/api/addons/AddonDescription.java

@@ -163,9 +163,12 @@ public ConfigurationSection getPermissions() {
     }
 
     public static class Builder {
-        private @NonNull String main;
-        private @NonNull String name;
-        private @NonNull String version;
+        private @NonNull
+        final String main;
+        private @NonNull
+        final String name;
+        private @NonNull
+        final String version;
         private @NonNull String description = "";
         private @NonNull List<String> authors = new ArrayList<>();
         private @NonNull List<String> dependencies = new ArrayList<>();

src/main/java/world/bentobox/bentobox/api/addons/request/AddonRequestBuilder.java

@@ -20,7 +20,7 @@ public class AddonRequestBuilder
 {
     private String addonName;
     private String requestLabel;
-    private Map<String, Object> metaData = new HashMap<>();
+    private final Map<String, Object> metaData = new HashMap<>();
 
     /**
      * Define the addon you wish to request.

src/main/java/world/bentobox/bentobox/api/commands/CompositeCommand.java

@@ -78,12 +78,12 @@ public abstract class CompositeCommand extends Command implements PluginIdentifi
     /**
      * Map of sub commands
      */
-    private Map<String, CompositeCommand> subCommands;
+    private final Map<String, CompositeCommand> subCommands;
 
     /**
      * Map of aliases for subcommands
      */
-    private Map<String, CompositeCommand> subCommandAliases;
+    private final Map<String, CompositeCommand> subCommandAliases;
     /**
      * The command chain from the very top, e.g., island team promote
      */
@@ -93,7 +93,7 @@ public abstract class CompositeCommand extends Command implements PluginIdentifi
      * The prefix to be used in this command
      */
     @Nullable
-    private String permissionPrefix;
+    private final String permissionPrefix;
 
     /**
      * The world that this command operates in. This is an overworld and will cover any associated nether or end
@@ -104,17 +104,17 @@ public abstract class CompositeCommand extends Command implements PluginIdentifi
     /**
      * The addon creating this command, if any
      */
-    private Addon addon;
+    private final Addon addon;
 
     /**
      * The top level label
      */
-    private String topLabel;
+    private final String topLabel;
 
     /**
      * Cool down tracker
      */
-    private Map<String, Map<String, Long>> cooldowns = new HashMap<>();
+    private final Map<String, Map<String, Long>> cooldowns = new HashMap<>();
 
     /**
      * Top level command

src/main/java/world/bentobox/bentobox/api/commands/ConfirmableCommand.java

@@ -20,7 +20,7 @@ public abstract class ConfirmableCommand extends CompositeCommand {
     /**
      * Confirmation tracker
      */
-    private static Map<User, Confirmer> toBeConfirmed = new HashMap<>();
+    private static final Map<User, Confirmer> toBeConfirmed = new HashMap<>();
 
     /**
      * Top level command

src/main/java/world/bentobox/bentobox/api/commands/DelayedTeleportCommand.java

@@ -26,7 +26,7 @@ public abstract class DelayedTeleportCommand extends CompositeCommand implements
     /**
      * User monitor map
      */
-    private static Map<UUID, DelayedCommand> toBeMonitored = new HashMap<>();
+    private static final Map<UUID, DelayedCommand> toBeMonitored = new HashMap<>();
 
     @EventHandler(priority = EventPriority.NORMAL, ignoreCancelled = true)
     public void onPlayerMove(PlayerMoveEvent e) {

src/main/java/world/bentobox/bentobox/api/commands/admin/AdminResetFlagsCommand.java

@@ -20,7 +20,7 @@
  */
 public class AdminResetFlagsCommand extends ConfirmableCommand {
 
-    private List<String> options;
+    private final List<String> options;
 
     public AdminResetFlagsCommand(CompositeCommand parent) {
         super(parent, "resetflags");

src/main/java/world/bentobox/bentobox/api/commands/admin/AdminSettingsCommand.java

@@ -38,7 +38,7 @@ public class AdminSettingsCommand extends CompositeCommand {
     private final List<String> PROTECTION_FLAG_NAMES;
     private Island island;
     private final List<String> SETTING_FLAG_NAMES;
-    private List<String> WORLD_SETTING_FLAG_NAMES;
+    private final List<String> WORLD_SETTING_FLAG_NAMES;
     private @NonNull Optional<Flag> flag = Optional.empty();
     private boolean activeState;
     private int rank;

src/main/java/world/bentobox/bentobox/api/commands/admin/range/AdminRangeDisplayCommand.java

@@ -24,7 +24,7 @@ public class AdminRangeDisplayCommand extends CompositeCommand {
     private static final String HIDE = "hide";
 
     // Map of users to which ranges must be displayed
-    private Map<User, Integer> displayRanges = new HashMap<>();
+    private final Map<User, Integer> displayRanges = new HashMap<>();
 
     public AdminRangeDisplayCommand(CompositeCommand parent) {
         super(parent, DISPLAY, SHOW, HIDE);

src/main/java/world/bentobox/bentobox/api/commands/island/team/IslandTeamCommand.java

@@ -29,7 +29,7 @@ public class IslandTeamCommand extends CompositeCommand {
      * Invited list. Key is the invited party, value is the invite.
      * @since 1.8.0
      */
-    private Map<UUID, Invite> inviteMap;
+    private final Map<UUID, Invite> inviteMap;
 
     public IslandTeamCommand(CompositeCommand parent) {
         super(parent, "team");

src/main/java/world/bentobox/bentobox/api/commands/island/team/IslandTeamCoopCommand.java

@@ -22,7 +22,7 @@
  */
 public class IslandTeamCoopCommand extends CompositeCommand {
 
-    private IslandTeamCommand itc;
+    private final IslandTeamCommand itc;
     private @Nullable UUID targetUUID;
 
     public IslandTeamCoopCommand(IslandTeamCommand parentCommand) {

src/main/java/world/bentobox/bentobox/api/commands/island/team/IslandTeamInviteAcceptCommand.java

@@ -20,7 +20,7 @@
  */
 public class IslandTeamInviteAcceptCommand extends ConfirmableCommand {
 
-    private IslandTeamCommand itc;
+    private final IslandTeamCommand itc;
     private UUID playerUUID;
     private UUID prospectiveOwnerUUID;
 

src/main/java/world/bentobox/bentobox/api/commands/island/team/IslandTeamInviteCommand.java

@@ -20,7 +20,7 @@
 
 public class IslandTeamInviteCommand extends CompositeCommand {
 
-    private IslandTeamCommand itc;
+    private final IslandTeamCommand itc;
     private @Nullable User invitedPlayer;
 
     public IslandTeamInviteCommand(IslandTeamCommand parent) {

src/main/java/world/bentobox/bentobox/api/commands/island/team/IslandTeamInviteRejectCommand.java

@@ -11,7 +11,7 @@
 
 public class IslandTeamInviteRejectCommand extends CompositeCommand {
 
-    private IslandTeamCommand itc;
+    private final IslandTeamCommand itc;
 
     public IslandTeamInviteRejectCommand(IslandTeamCommand islandTeamCommand) {
         super(islandTeamCommand, "reject");

src/main/java/world/bentobox/bentobox/api/configuration/Config.java

@@ -22,8 +22,8 @@
  */
 public class Config<T> {
 
-    private AbstractDatabaseHandler<T> handler;
-    private Logger logger;
+    private final AbstractDatabaseHandler<T> handler;
+    private final Logger logger;
     private Addon addon;
 
     public Config(BentoBox plugin, Class<T> type)  {

src/main/java/world/bentobox/bentobox/api/flags/Flag.java

@@ -53,7 +53,8 @@ public enum Type {
          */
         WORLD_SETTING(Material.GRASS_BLOCK);
 
-        private @NonNull Material icon;
+        private @NonNull
+        final Material icon;
 
         Type(@NonNull Material icon) {
             this.icon = icon;
@@ -482,8 +483,8 @@ public int compareTo(Flag o) {
      */
     public static class Builder {
         // Mandatory fields
-        private String id;
-        private Material icon;
+        private final String id;
+        private final Material icon;
 
         // Listener
         private Listener listener;
@@ -512,7 +513,7 @@ public static class Builder {
         private Mode mode = Mode.EXPERT;
 
         // Subflags
-        private Set<Flag> subflags;
+        private final Set<Flag> subflags;
 
         /**
          * Builder for making flags

src/main/java/world/bentobox/bentobox/api/flags/clicklisteners/IslandToggleClick.java

@@ -23,8 +23,8 @@
  */
 public class IslandToggleClick implements ClickHandler {
 
-    private BentoBox plugin = BentoBox.getInstance();
-    private String id;
+    private final BentoBox plugin = BentoBox.getInstance();
+    private final String id;
 
     /**
      * @param id - the flag ID that this click listener is associated with

src/main/java/world/bentobox/bentobox/api/localization/BentoBoxLocale.java

@@ -20,16 +20,16 @@ public class BentoBoxLocale {
 
     private static final String UNKNOWN = "unknown";
 
-    private Locale locale;
-    private YamlConfiguration config;
-    private ItemStack banner;
-    private List<String> authors;
+    private final Locale locale;
+    private final YamlConfiguration config;
+    private final ItemStack banner;
+    private final List<String> authors;
 
     /**
      * List of available prefixes in this locale.
      * @since 1.12.0
      */
-    private Set<String> prefixes;
+    private final Set<String> prefixes;
 
     public BentoBoxLocale(Locale locale, YamlConfiguration config) {
         this.locale = locale;

src/main/java/world/bentobox/bentobox/api/logs/LogEntry.java

@@ -47,7 +47,7 @@ public Map<String, String> getData() {
 
     public static class Builder {
         private long timestamp;
-        private String type;
+        private final String type;
         private Map<String, String> data;
 
         public Builder(@NonNull String type) {

src/main/java/world/bentobox/bentobox/api/panels/PanelItem.java

@@ -29,7 +29,7 @@ public static PanelItem empty() {
     private String name;
     private boolean glow;
     private ItemMeta meta;
-    private String playerHeadName;
+    private final String playerHeadName;
     private boolean invisible;
 
     public PanelItem(PanelItemBuilder builtItem) {

src/main/java/world/bentobox/bentobox/api/panels/TabbedPanel.java

@@ -31,7 +31,8 @@ public class TabbedPanel extends Panel implements PanelListener {
     private static final String PROTECTION_PANEL = "protection.panel.";
     private static final long ITEMS_PER_PAGE = 36;
     private final TabbedPanelBuilder tpb;
-    private @NonNull BentoBox plugin = BentoBox.getInstance();
+    private @NonNull
+    final BentoBox plugin = BentoBox.getInstance();
     private int activeTab;
     private int activePage;
     private boolean closed;

src/main/java/world/bentobox/bentobox/api/placeholders/placeholderapi/AddonPlaceholderExpansion.java

@@ -3,7 +3,7 @@
 import world.bentobox.bentobox.api.addons.Addon;
 
 public class AddonPlaceholderExpansion extends BasicPlaceholderExpansion {
-    private Addon addon;
+    private final Addon addon;
 
     public AddonPlaceholderExpansion(Addon addon) {
         this.addon = addon;

src/main/java/world/bentobox/bentobox/api/placeholders/placeholderapi/BasicPlaceholderExpansion.java

@@ -16,7 +16,7 @@
  */
 abstract class BasicPlaceholderExpansion extends PlaceholderExpansion {
     @NonNull
-    private Map<@NonNull String, @NonNull PlaceholderReplacer> placeholders;
+    private final Map<@NonNull String, @NonNull PlaceholderReplacer> placeholders;
 
     BasicPlaceholderExpansion() {
         super();

src/main/java/world/bentobox/bentobox/api/placeholders/placeholderapi/BentoBoxPlaceholderExpansion.java

@@ -3,7 +3,7 @@
 import world.bentobox.bentobox.BentoBox;
 
 public class BentoBoxPlaceholderExpansion extends BasicPlaceholderExpansion {
-    private BentoBox plugin;
+    private final BentoBox plugin;
 
     public BentoBoxPlaceholderExpansion(BentoBox plugin) {
         super();

src/main/java/world/bentobox/bentobox/api/user/User.java

@@ -47,7 +47,7 @@
  */
 public class User implements MetaDataAble {
 
-    private static Map<UUID, User> users = new HashMap<>();
+    private static final Map<UUID, User> users = new HashMap<>();
 
     /**
      * Clears all users from the user list
@@ -136,7 +136,7 @@ public static void removePlayer(Player player) {
     private static BentoBox plugin = BentoBox.getInstance();
 
     @Nullable
-    private Player player;
+    private final Player player;
     private OfflinePlayer offlinePlayer;
     private final UUID playerUUID;
     @Nullable

src/main/java/world/bentobox/bentobox/blueprints/BlueprintClipboard.java

@@ -63,10 +63,10 @@ public class BlueprintClipboard {
     private boolean copying;
     private int index;
     private int lastPercentage;
-    private Map<Vector, List<BlueprintEntity>> bpEntities = new LinkedHashMap<>();
-    private Map<Vector, BlueprintBlock> bpAttachable = new LinkedHashMap<>();
-    private Map<Vector, BlueprintBlock> bpBlocks = new LinkedHashMap<>();
-    private BentoBox plugin = BentoBox.getInstance();
+    private final Map<Vector, List<BlueprintEntity>> bpEntities = new LinkedHashMap<>();
+    private final Map<Vector, BlueprintBlock> bpAttachable = new LinkedHashMap<>();
+    private final Map<Vector, BlueprintBlock> bpBlocks = new LinkedHashMap<>();
+    private final BentoBox plugin = BentoBox.getInstance();
 
     /**
      * Create a clipboard for blueprint

src/main/java/world/bentobox/bentobox/blueprints/BlueprintPaster.java

@@ -72,7 +72,7 @@ enum PasteState {
 
     private static final Map<String, String> BLOCK_CONVERSION = ImmutableMap.of("sign", "oak_sign", "wall_sign", "oak_wall_sign");
 
-    private BentoBox plugin;
+    private final BentoBox plugin;
     // The minimum block position (x,y,z)
     private Location pos1;
     // The maximum block position (x,y,z)
@@ -85,19 +85,19 @@ enum PasteState {
      * The Blueprint to paste.
      */
     @NonNull
-    private Blueprint blueprint;
+    private final Blueprint blueprint;
 
     /**
      * The Location to paste to.
      */
     @NonNull
-    private Location location;
+    private final Location location;
 
     /**
      * Island related to this paste, may be null.
      */
     @Nullable
-    private Island island;
+    private final Island island;
 
     /**
      * Paste a clipboard to a location and run task

src/main/java/world/bentobox/bentobox/blueprints/conversation/DescriptionPrompt.java

@@ -23,8 +23,8 @@
 public class DescriptionPrompt extends StringPrompt {
 
     private static final String DESCRIPTION = "description";
-    private GameModeAddon addon;
-    private BlueprintBundle bb;
+    private final GameModeAddon addon;
+    private final BlueprintBundle bb;
 
     public DescriptionPrompt(GameModeAddon addon, BlueprintBundle bb) {
         this.addon = addon;

src/main/java/world/bentobox/bentobox/blueprints/conversation/DescriptionSuccessPrompt.java

@@ -15,8 +15,8 @@
 
 public class DescriptionSuccessPrompt extends MessagePrompt {
 
-    private GameModeAddon addon;
-    private BlueprintBundle bb;
+    private final GameModeAddon addon;
+    private final BlueprintBundle bb;
 
     /**
      * @param addon game mode addon