Fixed non-final params

# Conflicts:
#	gradle.properties

build.gradle

@@ -51,6 +51,9 @@ allprojects {
 
         // CombatLogX
         maven { url 'https://nexus.sirblobman.xyz/repository/public/' }
+
+        // Head Database
+        maven { url 'https://mvn.intellectualsites.com/content/groups/public/' }
     }
 
     dependencies {

eco-api/src/main/java/com/willfp/eco/core/EcoPlugin.java

@@ -305,10 +305,27 @@ public abstract class EcoPlugin extends JavaPlugin {
         this.logger = Eco.getHandler().createLogger(this);
         this.proxyFactory = this.proxyPackage.equalsIgnoreCase("") ? null : Eco.getHandler().createProxyFactory(this);
 
-        this.langYml = new LangYml(this);
-        this.configYml = new ConfigYml(this);
+        this.langYml = this.createLangYml();
+        this.configYml = this.createConfigYml();
 
         Eco.getHandler().addNewPlugin(this);
+
+        /*
+        The minimum eco version check was moved here because it's very common
+        to add a lot of code in the constructor of plugins; meaning that the plugin
+        can throw errors without it being obvious to the user that the reason is
+        because they have an outdated version of eco installed.
+         */
+
+        DefaultArtifactVersion runningVersion = new DefaultArtifactVersion(Eco.getHandler().getEcoPlugin().getDescription().getVersion());
+        DefaultArtifactVersion requiredVersion = new DefaultArtifactVersion(this.getMinimumEcoVersion());
+        if (!(runningVersion.compareTo(requiredVersion) > 0 || runningVersion.equals(requiredVersion))) {
+            this.getLogger().severe("You are running an outdated version of eco!");
+            this.getLogger().severe("You must be on at least" + this.getMinimumEcoVersion());
+            this.getLogger().severe("Download the newest version here:");
+            this.getLogger().severe("https://polymart.org/download/773/recent/JSpprMspkuyecf5y1wQ2Jn8OoLQSQ_IW");
+            Bukkit.getPluginManager().disablePlugin(this);
+        }
     }
 
     /**
@@ -336,29 +353,22 @@ public abstract class EcoPlugin extends JavaPlugin {
             });
         }
 
-        DefaultArtifactVersion runningVersion = new DefaultArtifactVersion(Eco.getHandler().getEcoPlugin().getDescription().getVersion());
-        DefaultArtifactVersion requiredVersion = new DefaultArtifactVersion(this.getMinimumEcoVersion());
-        if (!(runningVersion.compareTo(requiredVersion) > 0 || runningVersion.equals(requiredVersion))) {
-            this.getLogger().severe("You are running an outdated version of eco!");
-            this.getLogger().severe("You must be on at least" + this.getMinimumEcoVersion());
-            this.getLogger().severe("Download the newest version here:");
-            this.getLogger().severe("https://polymart.org/download/773/recent/JSpprMspkuyecf5y1wQ2Jn8OoLQSQ_IW");
-            Bukkit.getPluginManager().disablePlugin(this);
-        }
-
         if (this.getBStatsId() != 0) {
             Eco.getHandler().registerBStats(this);
         }
 
-        Set<String> enabledPlugins = Arrays.stream(Bukkit.getPluginManager().getPlugins()).map(Plugin::getName).collect(Collectors.toSet());
+        Set<String> enabledPlugins = Arrays.stream(Bukkit.getPluginManager().getPlugins())
+                .map(Plugin::getName)
+                .map(String::toLowerCase)
+                .collect(Collectors.toSet());
 
-        if (enabledPlugins.contains("PlaceholderAPI")) {
+        if (enabledPlugins.contains("PlaceholderAPI".toLowerCase())) {
             this.loadedIntegrations.add("PlaceholderAPI");
             PlaceholderManager.addIntegration(Eco.getHandler().createPAPIIntegration(this));
         }
 
         this.loadIntegrationLoaders().forEach((integrationLoader -> {
-            if (enabledPlugins.contains(integrationLoader.getPluginName())) {
+            if (enabledPlugins.contains(integrationLoader.getPluginName().toLowerCase())) {
                 this.loadedIntegrations.add(integrationLoader.getPluginName());
                 integrationLoader.load();
             }
@@ -571,6 +581,28 @@ public abstract class EcoPlugin extends JavaPlugin {
      */
     protected abstract List<Listener> loadListeners();
 
+    /**
+     * Useful for custom LangYml implementations.
+     * <p>
+     * Override if needed.
+     *
+     * @return lang.yml.
+     */
+    protected LangYml createLangYml() {
+        return new LangYml(this);
+    }
+
+    /**
+     * Useful for custom ConfigYml implementations.
+     * <p>
+     * Override if needed.
+     *
+     * @return config.yml.
+     */
+    protected ConfigYml createConfigYml() {
+        return new ConfigYml(this);
+    }
+
     /**
      * Create the display module for the plugin.
      *

eco-api/src/main/java/com/willfp/eco/core/Handler.java

@@ -13,9 +13,11 @@ import com.willfp.eco.core.gui.GUIFactory;
 import com.willfp.eco.core.integrations.placeholder.PlaceholderIntegration;
 import com.willfp.eco.core.proxy.Cleaner;
 import com.willfp.eco.core.proxy.ProxyFactory;
+import com.willfp.eco.core.requirement.RequirementFactory;
 import com.willfp.eco.core.scheduling.Scheduler;
 import org.bukkit.inventory.ItemStack;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 import java.util.List;
 import java.util.logging.Logger;
@@ -30,6 +32,7 @@ public interface Handler {
      * @param plugin The plugin.
      * @return The scheduler.
      */
+    @NotNull
     Scheduler createScheduler(@NotNull EcoPlugin plugin);
 
     /**
@@ -38,6 +41,7 @@ public interface Handler {
      * @param plugin The plugin.
      * @return The event manager.
      */
+    @NotNull
     EventManager createEventManager(@NotNull EcoPlugin plugin);
 
     /**
@@ -46,6 +50,7 @@ public interface Handler {
      * @param plugin The plugin.
      * @return The factory.
      */
+    @NotNull
     NamespacedKeyFactory createNamespacedKeyFactory(@NotNull EcoPlugin plugin);
 
     /**
@@ -54,6 +59,7 @@ public interface Handler {
      * @param plugin The plugin.
      * @return The factory.
      */
+    @NotNull
     MetadataValueFactory createMetadataValueFactory(@NotNull EcoPlugin plugin);
 
     /**
@@ -62,6 +68,7 @@ public interface Handler {
      * @param plugin The plugin.
      * @return The factory.
      */
+    @NotNull
     RunnableFactory createRunnableFactory(@NotNull EcoPlugin plugin);
 
     /**
@@ -70,6 +77,7 @@ public interface Handler {
      * @param plugin The plugin.
      * @return The factory.
      */
+    @NotNull
     ExtensionLoader createExtensionLoader(@NotNull EcoPlugin plugin);
 
     /**
@@ -78,6 +86,7 @@ public interface Handler {
      * @param plugin The plugin.
      * @return The handler.
      */
+    @NotNull
     ConfigHandler createConfigHandler(@NotNull EcoPlugin plugin);
 
     /**
@@ -86,6 +95,7 @@ public interface Handler {
      * @param plugin The plugin.
      * @return The logger.
      */
+    @NotNull
     Logger createLogger(@NotNull EcoPlugin plugin);
 
     /**
@@ -94,6 +104,7 @@ public interface Handler {
      * @param plugin The plugin.
      * @return The integration.
      */
+    @NotNull
     PlaceholderIntegration createPAPIIntegration(@NotNull EcoPlugin plugin);
 
     /**
@@ -102,6 +113,7 @@ public interface Handler {
      * @param plugin The plugin.
      * @return The factory.
      */
+    @NotNull
     ProxyFactory createProxyFactory(@NotNull EcoPlugin plugin);
 
     /**
@@ -109,6 +121,7 @@ public interface Handler {
      *
      * @return The plugin.
      */
+    @NotNull
     EcoPlugin getEcoPlugin();
 
     /**
@@ -116,6 +129,7 @@ public interface Handler {
      *
      * @return The factory.
      */
+    @NotNull
     ConfigFactory getConfigFactory();
 
     /**
@@ -123,6 +137,7 @@ public interface Handler {
      *
      * @return The factory.
      */
+    @NotNull
     DropQueueFactory getDropQueueFactory();
 
     /**
@@ -130,6 +145,7 @@ public interface Handler {
      *
      * @return The factory.
      */
+    @NotNull
     GUIFactory getGUIFactory();
 
     /**
@@ -137,6 +153,7 @@ public interface Handler {
      *
      * @return The cleaner.
      */
+    @NotNull
     Cleaner getCleaner();
 
     /**
@@ -152,6 +169,7 @@ public interface Handler {
      * @param name The name.
      * @return The plugin.
      */
+    @Nullable
     EcoPlugin getPluginByName(@NotNull String name);
 
     /**
@@ -159,6 +177,7 @@ public interface Handler {
      *
      * @return A list of plugin names in lowercase.
      */
+    @NotNull
     List<String> getLoadedPlugins();
 
     /**
@@ -167,6 +186,7 @@ public interface Handler {
      * @param itemStack The base ItemStack.
      * @return The FastItemStack.
      */
+    @NotNull
     FastItemStack createFastItemStack(@NotNull ItemStack itemStack);
 
     /**
@@ -175,4 +195,11 @@ public interface Handler {
      * @param plugin The plugin.
      */
     void registerBStats(@NotNull EcoPlugin plugin);
+
+    /**
+     * Get the requirement factory.
+     *
+     * @return The factory.
+     */
+    RequirementFactory getRequirementFactory();
 }

eco-api/src/main/java/com/willfp/eco/core/PluginDependent.java

@@ -9,11 +9,12 @@ import org.jetbrains.annotations.NotNull;
  *
  * @param <T> The eco plugin type.
  */
-public abstract class PluginDependent<T extends EcoPlugin> {
+public abstract class PluginDependent<@NotNull T extends EcoPlugin> {
     /**
      * The {@link EcoPlugin} that is stored.
      */
     @Getter(AccessLevel.PROTECTED)
+    @NotNull
     private final T plugin;
 
     /**

eco-api/src/main/java/com/willfp/eco/core/config/json/JSONBaseConfig.java

@@ -0,0 +1,54 @@
+package com.willfp.eco.core.config.json;
+
+import com.willfp.eco.core.Eco;
+import com.willfp.eco.core.EcoPlugin;
+import com.willfp.eco.core.config.json.wrapper.LoadableJSONConfigWrapper;
+import com.willfp.eco.core.config.yaml.wrapper.LoadableYamlConfigWrapper;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Config implementation for configs present in the plugin's base directory (eg config.json).
+ * <p>
+ * Automatically updates.
+ */
+public abstract class JSONBaseConfig extends LoadableJSONConfigWrapper {
+    /**
+     * @param configName      The name of the config
+     * @param removeUnused    Whether keys not present in the default config should be removed on update.
+     * @param plugin          The plugin.
+     * @param updateBlacklist Substring of keys to not add/remove keys for.
+     */
+    protected JSONBaseConfig(@NotNull final String configName,
+                             final boolean removeUnused,
+                             @NotNull final EcoPlugin plugin,
+                             @NotNull final String... updateBlacklist) {
+        super(
+                Eco.getHandler().getConfigFactory().createUpdatableJSONConfig(
+                        configName,
+                        plugin,
+                        "",
+                        plugin.getClass(),
+                        removeUnused, updateBlacklist
+                )
+        );
+    }
+
+    /**
+     * @param configName   The name of the config
+     * @param removeUnused Whether keys not present in the default config should be removed on update.
+     * @param plugin       The plugin.
+     */
+    protected JSONBaseConfig(@NotNull final String configName,
+                             final boolean removeUnused,
+                             @NotNull final EcoPlugin plugin) {
+        super(
+                Eco.getHandler().getConfigFactory().createUpdatableJSONConfig(
+                        configName,
+                        plugin,
+                        "",
+                        plugin.getClass(),
+                        removeUnused
+                )
+        );
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/config/json/JSONExtendableConfig.java

@@ -0,0 +1,44 @@
+package com.willfp.eco.core.config.json;
+
+import com.willfp.eco.core.Eco;
+import com.willfp.eco.core.EcoPlugin;
+import com.willfp.eco.core.config.json.wrapper.LoadableJSONConfigWrapper;
+import com.willfp.eco.core.config.yaml.wrapper.LoadableYamlConfigWrapper;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Config implementation for configs present in one of two places:
+ * <ul>
+ *     <li>Plugin base directory (eg config.yml, lang.yml)</li>
+ *     <li>Other extension's configs</li>
+ * </ul>
+ * <p>
+ * Automatically updates.
+ */
+public abstract class JSONExtendableConfig extends LoadableJSONConfigWrapper {
+    /**
+     * @param configName       The name of the config
+     * @param removeUnused     Whether keys not present in the default config should be removed on update.
+     * @param plugin           The plugin.
+     * @param updateBlacklist  Substring of keys to not add/remove keys for.
+     * @param subDirectoryPath The subdirectory path.
+     * @param source           The class that owns the resource.
+     */
+    protected JSONExtendableConfig(@NotNull final String configName,
+                                   final boolean removeUnused,
+                                   @NotNull final EcoPlugin plugin,
+                                   @NotNull final Class<?> source,
+                                   @NotNull final String subDirectoryPath,
+                                   @NotNull final String... updateBlacklist) {
+        super(
+                Eco.getHandler().getConfigFactory().createUpdatableJSONConfig(
+                        configName,
+                        plugin,
+                        subDirectoryPath,
+                        source,
+                        removeUnused,
+                        updateBlacklist
+                )
+        );
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/config/wrapper/ConfigFactory.java

@@ -30,6 +30,24 @@ public interface ConfigFactory {
                                      boolean removeUnused,
                                      @NotNull String... updateBlacklist);
 
+    /**
+     * Updatable config.
+     *
+     * @param configName       The name of the config
+     * @param plugin           The plugin.
+     * @param subDirectoryPath The subdirectory path.
+     * @param source           The class that owns the resource.
+     * @param removeUnused     Whether keys not present in the default config should be removed on update.
+     * @param updateBlacklist  Substring of keys to not add/remove keys for.
+     * @return The config implementation.
+     */
+    JSONConfig createUpdatableJSONConfig(@NotNull String configName,
+                                         @NotNull EcoPlugin plugin,
+                                         @NotNull String subDirectoryPath,
+                                         @NotNull Class<?> source,
+                                         boolean removeUnused,
+                                         @NotNull String... updateBlacklist);
+
     /**
      * JSON loadable config.
      *

eco-api/src/main/java/com/willfp/eco/core/display/Display.java

@@ -1,22 +1,12 @@
 package com.willfp.eco.core.display;
 
 import lombok.experimental.UtilityClass;
-import org.apache.commons.lang.Validate;
-import org.bukkit.NamespacedKey;
 import org.bukkit.entity.Player;
 import org.bukkit.inventory.ItemStack;
-import org.bukkit.inventory.meta.ItemMeta;
-import org.bukkit.persistence.PersistentDataContainer;
-import org.bukkit.persistence.PersistentDataType;
 import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
-import java.util.ArrayList;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
-
 /**
  * Utility class to manage client-side item display.
  */
@@ -28,29 +18,9 @@ public class Display {
     public static final String PREFIX = "§z";
 
     /**
-     * All registered display modules.
+     * The display handler.
      */
-    private static final Map<DisplayPriority, List<DisplayModule>> MODULES = new HashMap<>();
-
-    /**
-     * NamespacedKey for finalizing.
-     */
-    private static NamespacedKey finalizeKey = null;
-
-    /**
-     * Register display module.
-     *
-     * @param module The module.
-     */
-    public void registerDisplayModule(@NotNull final DisplayModule module) {
-        List<DisplayModule> modules = MODULES.get(module.getPriority());
-
-        modules.removeIf(module1 -> module1.getPluginName().equalsIgnoreCase(module.getPluginName()));
-
-        modules.add(module);
-
-        MODULES.put(module.getPriority(), modules);
-    }
+    public static DisplayHandler handler = null;
 
     /**
      * Display on ItemStacks.
@@ -71,35 +41,7 @@ public class Display {
      */
     public ItemStack display(@NotNull final ItemStack itemStack,
                              @Nullable final Player player) {
-        Map<String, Object[]> pluginVarArgs = new HashMap<>();
-
-        for (DisplayPriority priority : DisplayPriority.values()) {
-            List<DisplayModule> modules = MODULES.get(priority);
-            for (DisplayModule module : modules) {
-                pluginVarArgs.put(module.getPluginName(), module.generateVarArgs(itemStack));
-            }
-        }
-
-        revert(itemStack);
-
-        ItemMeta meta = itemStack.getItemMeta();
-
-        if (meta == null) {
-            return itemStack;
-        }
-
-        for (DisplayPriority priority : DisplayPriority.values()) {
-            List<DisplayModule> modules = MODULES.get(priority);
-            for (DisplayModule module : modules) {
-                Object[] varargs = pluginVarArgs.get(module.getPluginName());
-                module.display(itemStack, varargs);
-                if (player != null) {
-                    module.display(itemStack, player, varargs);
-                }
-            }
-        }
-
-        return itemStack;
+        return handler.display(itemStack, player);
     }
 
     /**
@@ -131,31 +73,7 @@ public class Display {
      * @return The ItemStack.
      */
     public ItemStack revert(@NotNull final ItemStack itemStack) {
-        if (Display.isFinalized(itemStack)) {
-            unfinalize(itemStack);
-        }
-
-        ItemMeta meta = itemStack.getItemMeta();
-
-        if (meta == null) {
-            return itemStack;
-        }
-
-        List<String> lore = meta.getLore();
-
-        if (lore != null && lore.removeIf(line -> line.startsWith(Display.PREFIX))) { // only apply lore modification if needed
-            meta.setLore(lore);
-            itemStack.setItemMeta(meta);
-        }
-
-        for (DisplayPriority priority : DisplayPriority.values()) {
-            List<DisplayModule> modules = MODULES.get(priority);
-            for (DisplayModule module : modules) {
-                module.revert(itemStack);
-            }
-        }
-
-        return itemStack;
+        return handler.revert(itemStack);
     }
 
     /**
@@ -165,21 +83,7 @@ public class Display {
      * @return The ItemStack.
      */
     public ItemStack finalize(@NotNull final ItemStack itemStack) {
-        Validate.notNull(finalizeKey, "Key cannot be null!");
-
-        if (itemStack.getType().getMaxStackSize() > 1) {
-            return itemStack;
-        }
-
-        ItemMeta meta = itemStack.getItemMeta();
-        if (meta == null) {
-            return itemStack;
-        }
-
-        PersistentDataContainer container = meta.getPersistentDataContainer();
-        container.set(finalizeKey, PersistentDataType.INTEGER, 1);
-        itemStack.setItemMeta(meta);
-        return itemStack;
+        return handler.finalize(itemStack);
     }
 
     /**
@@ -189,18 +93,7 @@ public class Display {
      * @return The ItemStack.
      */
     public ItemStack unfinalize(@NotNull final ItemStack itemStack) {
-        Validate.notNull(finalizeKey, "Key cannot be null!");
-
-        ItemMeta meta = itemStack.getItemMeta();
-
-        if (meta == null) {
-            return itemStack;
-        }
-
-        PersistentDataContainer container = meta.getPersistentDataContainer();
-        container.remove(finalizeKey);
-        itemStack.setItemMeta(meta);
-        return itemStack;
+        return handler.unfinalize(itemStack);
     }
 
     /**
@@ -210,31 +103,62 @@ public class Display {
      * @return If finalized.
      */
     public boolean isFinalized(@NotNull final ItemStack itemStack) {
-        Validate.notNull(finalizeKey, "Key cannot be null!");
-
-        ItemMeta meta = itemStack.getItemMeta();
-
-        if (meta == null) {
-            return false;
-        }
-
-        PersistentDataContainer container = meta.getPersistentDataContainer();
-        return container.has(finalizeKey, PersistentDataType.INTEGER);
+        return handler.isFinalized(itemStack);
     }
 
     /**
-     * Set key to be used for finalization.
+     * Register a new display module.
      *
-     * @param finalizeKey The key.
+     * @param module The module.
      */
-    @ApiStatus.Internal
-    public static void setFinalizeKey(@NotNull final NamespacedKey finalizeKey) {
-        Display.finalizeKey = finalizeKey;
+    public void registerDisplayModule(@NotNull final DisplayModule module) {
+        handler.registerDisplayModule(module);
     }
 
-    static {
-        for (DisplayPriority priority : DisplayPriority.values()) {
-            MODULES.put(priority, new ArrayList<>());
+    /**
+     * Initialize the display system.
+     *
+     * @param handler The handler.
+     */
+    @ApiStatus.Internal
+    public static void init(@NotNull final DisplayHandler handler) {
+        if (Display.handler != null) {
+            throw new IllegalArgumentException("Already Initialized!");
+        }
+        Display.handler = handler;
+    }
+
+    /**
+     * Extremely janky method - also internal, so don't use it. <b>This method is
+     * NOT part of the API and may be removed at any time!</b>
+     * <p>
+     * This calls a display module with the specified parameters, now
+     * you might ask why I need a static java method when the DisplayHandler
+     * implementation could just call it itself? Well, kotlin doesn't really
+     * like dealing with vararg ambiguity, and so while kotlin can't figure out
+     * what is and isn't a vararg when I call display with a player, java can.
+     * <p>
+     * Because of this, I need to have this part of the code in java.
+     *
+     * <b>Don't call this method as part of your plugins!</b>
+     * <p>
+     * No, seriously - don't. This skips a bunch of checks and you'll almost
+     * definitely break something.
+     *
+     * @param module    The display module.
+     * @param itemStack The ItemStack.
+     * @param player    The player.
+     * @param args      The args.
+     */
+    @SuppressWarnings("checkstyle:FinalParameters")
+    @ApiStatus.Internal
+    public static void callDisplayModule(@NotNull final DisplayModule module,
+                                         @NotNull final ItemStack itemStack,
+                                         @Nullable final Player player,
+                                         @NotNull final Object... args) {
+        module.display(itemStack, args);
+        if (player != null) {
+            module.display(itemStack, player, args);
         }
     }
 }

eco-api/src/main/java/com/willfp/eco/core/display/DisplayHandler.java

@@ -0,0 +1,60 @@
+package com.willfp.eco.core.display;
+
+import org.bukkit.entity.Player;
+import org.bukkit.inventory.ItemStack;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * Interface for display implementations.
+ */
+public interface DisplayHandler {
+    /**
+     * Register display module.
+     *
+     * @param module The module.
+     */
+    void registerDisplayModule(@NotNull DisplayModule module);
+
+    /**
+     * Display on ItemStacks.
+     *
+     * @param itemStack The item.
+     * @param player    The player.
+     * @return The ItemStack.
+     */
+    ItemStack display(@NotNull final ItemStack itemStack,
+                      @Nullable final Player player);
+
+    /**
+     * Revert on ItemStacks.
+     *
+     * @param itemStack The item.
+     * @return The ItemStack.
+     */
+    ItemStack revert(@NotNull final ItemStack itemStack);
+
+    /**
+     * Finalize an ItemStacks.
+     *
+     * @param itemStack The item.
+     * @return The ItemStack.
+     */
+    ItemStack finalize(@NotNull final ItemStack itemStack);
+
+    /**
+     * Unfinalize an ItemStacks.
+     *
+     * @param itemStack The item.
+     * @return The ItemStack.
+     */
+    ItemStack unfinalize(@NotNull final ItemStack itemStack);
+
+    /**
+     * If an item is finalized.
+     *
+     * @param itemStack The item.
+     * @return If finalized.
+     */
+    boolean isFinalized(@NotNull final ItemStack itemStack);
+}

eco-api/src/main/java/com/willfp/eco/core/display/DisplayModule.java

@@ -36,8 +36,8 @@ public abstract class DisplayModule extends PluginDependent<EcoPlugin> {
      * @param itemStack The item.
      * @param args      Optional args for display.
      */
-    protected void display(@NotNull final ItemStack itemStack,
-                           @NotNull final Object... args) {
+    public void display(@NotNull final ItemStack itemStack,
+                        @NotNull final Object... args) {
         // Technically optional.
     }
 
@@ -48,9 +48,9 @@ public abstract class DisplayModule extends PluginDependent<EcoPlugin> {
      * @param player    The player.
      * @param args      Optional args for display.
      */
-    protected void display(@NotNull final ItemStack itemStack,
-                           @Nullable final Player player,
-                           @NotNull final Object... args) {
+    public void display(@NotNull final ItemStack itemStack,
+                        @Nullable final Player player,
+                        @NotNull final Object... args) {
         // Technically optional.
     }
 
@@ -59,7 +59,7 @@ public abstract class DisplayModule extends PluginDependent<EcoPlugin> {
      *
      * @param itemStack The item.
      */
-    protected void revert(@NotNull final ItemStack itemStack) {
+    public void revert(@NotNull final ItemStack itemStack) {
         // Technically optional.
     }
 
@@ -69,7 +69,7 @@ public abstract class DisplayModule extends PluginDependent<EcoPlugin> {
      * @param itemStack The itemStack.
      * @return The plugin-specific varargs.
      */
-    protected Object[] generateVarArgs(@NotNull final ItemStack itemStack) {
+    public Object[] generateVarArgs(@NotNull final ItemStack itemStack) {
         return new Object[0];
     }
 

eco-api/src/main/java/com/willfp/eco/core/integrations/customitems/CustomItemsWrapper.java

@@ -1,9 +1,11 @@
 package com.willfp.eco.core.integrations.customitems;
 
+import com.willfp.eco.core.integrations.Integration;
+
 /**
  * Wrapper class for custom item integrations.
  */
-public interface CustomItemsWrapper {
+public interface CustomItemsWrapper extends Integration {
     /**
      * Register all the custom items for a specific plugin into eco.
      *

eco-api/src/main/java/com/willfp/eco/core/integrations/placeholder/PlaceholderManager.java

@@ -5,7 +5,9 @@ import org.bukkit.entity.Player;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
+import java.util.HashMap;
 import java.util.HashSet;
+import java.util.Map;
 import java.util.Optional;
 import java.util.Set;
 import java.util.concurrent.atomic.AtomicReference;
@@ -18,7 +20,7 @@ public class PlaceholderManager {
     /**
      * All registered placeholders.
      */
-    private static final Set<PlaceholderEntry> REGISTERED_PLACEHOLDERS = new HashSet<>();
+    private static final Map<String, PlaceholderEntry> REGISTERED_PLACEHOLDERS = new HashMap<>();
 
     /**
      * All registered placeholder integrations.
@@ -41,8 +43,8 @@ public class PlaceholderManager {
      * @param expansion The {@link PlaceholderEntry} to register.
      */
     public static void registerPlaceholder(@NotNull final PlaceholderEntry expansion) {
-        REGISTERED_PLACEHOLDERS.removeIf(placeholderEntry -> placeholderEntry.getIdentifier().equalsIgnoreCase(expansion.getIdentifier()));
-        REGISTERED_PLACEHOLDERS.add(expansion);
+        REGISTERED_PLACEHOLDERS.remove(expansion.getIdentifier());
+        REGISTERED_PLACEHOLDERS.put(expansion.getIdentifier(), expansion);
     }
 
     /**
@@ -54,14 +56,15 @@ public class PlaceholderManager {
      */
     public static String getResult(@Nullable final Player player,
                                    @NotNull final String identifier) {
-        Optional<PlaceholderEntry> matching = REGISTERED_PLACEHOLDERS.stream().filter(expansion -> expansion.getIdentifier().equalsIgnoreCase(identifier)).findFirst();
-        if (matching.isEmpty()) {
+        PlaceholderEntry entry = REGISTERED_PLACEHOLDERS.get(identifier.toLowerCase());
+        if (entry == null) {
             return "";
         }
-        PlaceholderEntry entry = matching.get();
+
         if (player == null && entry.requiresPlayer()) {
             return "";
         }
+
         return entry.getResult(player);
     }
 
@@ -74,8 +77,10 @@ public class PlaceholderManager {
      */
     public static String translatePlaceholders(@NotNull final String text,
                                                @Nullable final Player player) {
-        AtomicReference<String> translatedReference = new AtomicReference<>(text);
-        REGISTERED_INTEGRATIONS.forEach(placeholderIntegration -> translatedReference.set(placeholderIntegration.translate(translatedReference.get(), player)));
-        return translatedReference.get();
+        String processed = text;
+        for (PlaceholderIntegration integration : REGISTERED_INTEGRATIONS) {
+            processed = integration.translate(processed, player);
+        }
+        return processed;
     }
 }

eco-api/src/main/java/com/willfp/eco/core/integrations/shop/ShopWrapper.java

@@ -1,9 +1,11 @@
 package com.willfp.eco.core.integrations.shop;
 
+import com.willfp.eco.core.integrations.Integration;
+
 /**
  * Wrapper class for shop integrations.
  */
-public interface ShopWrapper {
+public interface ShopWrapper extends Integration {
     /**
      * Register eco item provider for shop plugins.
      */

eco-api/src/main/java/com/willfp/eco/core/items/CustomItem.java

@@ -1,6 +1,9 @@
 package com.willfp.eco.core.items;
 
+import com.willfp.eco.core.Eco;
 import lombok.Getter;
+import org.apache.commons.lang.Validate;
+import org.bukkit.Bukkit;
 import org.bukkit.NamespacedKey;
 import org.bukkit.inventory.ItemStack;
 import org.jetbrains.annotations.NotNull;
@@ -47,6 +50,12 @@ public class CustomItem implements TestableItem {
         this.key = key;
         this.test = test;
         this.item = item;
+
+        Eco.getHandler().getEcoPlugin().getScheduler().runLater(() -> {
+            if (!matches(getItem())) {
+                Bukkit.getLogger().severe("Item with key " + key + " is invalid!");
+            }
+        }, 1);
     }
 
     @Override

eco-api/src/main/java/com/willfp/eco/core/items/Items.java

@@ -1,5 +1,6 @@
 package com.willfp.eco.core.items;
 
+import com.willfp.eco.core.items.args.LookupArgParser;
 import com.willfp.eco.core.recipe.parts.EmptyTestableItem;
 import com.willfp.eco.core.recipe.parts.MaterialTestableItem;
 import com.willfp.eco.core.recipe.parts.ModifiedTestableItem;
@@ -8,18 +9,19 @@ import com.willfp.eco.util.NamespacedKeyUtils;
 import lombok.experimental.UtilityClass;
 import org.bukkit.Material;
 import org.bukkit.NamespacedKey;
-import org.bukkit.enchantments.Enchantment;
 import org.bukkit.inventory.ItemStack;
-import org.bukkit.inventory.meta.EnchantmentStorageMeta;
 import org.bukkit.inventory.meta.ItemMeta;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
+import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.HashMap;
 import java.util.HashSet;
+import java.util.List;
 import java.util.Map;
 import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.function.Predicate;
 
 /**
  * Class to manage all custom and vanilla items.
@@ -29,19 +31,33 @@ public final class Items {
     /**
      * All recipe parts.
      */
-    private static final Map<NamespacedKey, CustomItem> REGISTRY = new HashMap<>();
+    private static final Map<NamespacedKey, CustomItem> REGISTRY = new ConcurrentHashMap<>();
 
     /**
-     * Register a new recipe part.
+     * All recipe parts.
+     */
+    private static final List<LookupArgParser> ARG_PARSERS = new ArrayList<>();
+
+    /**
+     * Register a new custom item.
      *
-     * @param key  The key of the recipe part.
-     * @param part The recipe part.
+     * @param key  The key of the item.
+     * @param part The item.
      */
     public void registerCustomItem(@NotNull final NamespacedKey key,
                                    @NotNull final CustomItem part) {
         REGISTRY.put(key, part);
     }
 
+    /**
+     * Register a new arg parser.
+     *
+     * @param parser The parser.
+     */
+    public void registerArgParser(@NotNull final LookupArgParser parser) {
+        ARG_PARSERS.add(parser);
+    }
+
     /**
      * Remove an item.
      *
@@ -52,12 +68,27 @@ public final class Items {
     }
 
     /**
-     * Lookup item from string.
+     * This is the backbone of the entire eco item system.
      * <p>
-     * Used for recipes.
+     * You can lookup a TestableItem for any material, custom item,
+     * or item in general, and it will return it with any modifiers
+     * passed as parameters. This includes stack size (item amount)
+     * and enchantments that should be present on the item.
+     * <p>
+     * If you want to get an ItemStack instance from this, then just call
+     * {@link TestableItem#getItem()}.
+     * <p>
+     * The advantages of the testable item system are that there is the inbuilt
+     * {@link TestableItem#matches(ItemStack)} - this allows to check if any item
+     * is that testable item; which may sound negligible but actually it allows for
+     * much more power an flexibility. For example, you can have an item with an
+     * extra metadata tag, extra lore lines, different display name - and it
+     * will still work as long as the test passes. This is very important
+     * for custom crafting recipes where other plugins may add metadata
+     * values or the play may rename the item.
      *
-     * @param key The string to test.
-     * @return The found testable item, or an empty item if not found.
+     * @param key The lookup string.
+     * @return The testable item, or an {@link EmptyTestableItem}.
      */
     public TestableItem lookup(@NotNull final String key) {
         if (key.contains("?")) {
@@ -79,6 +110,8 @@ public final class Items {
 
         TestableItem item = null;
 
+        int stackAmount = 1;
+
         String[] split = args[0].toLowerCase().split(":");
 
         if (split.length == 1) {
@@ -92,90 +125,87 @@ public final class Items {
         if (split.length == 2) {
             CustomItem part = REGISTRY.get(NamespacedKeyUtils.create(split[0], split[1]));
 
+            /*
+            Legacy id:amount format
+            This has been superseded by id amount
+             */
             if (part == null) {
                 Material material = Material.getMaterial(split[0].toUpperCase());
                 if (material == null || material == Material.AIR) {
                     return new EmptyTestableItem();
                 }
-                item = new TestableStack(new MaterialTestableItem(material), Integer.parseInt(split[1]));
+                item = new MaterialTestableItem(material);
+                stackAmount = Integer.parseInt(split[1]);
             } else {
                 item = part;
             }
         }
 
+        /*
+        Legacy namespace:id:amount format
+        This has been superseded by namespace:id amount
+         */
         if (split.length == 3) {
             CustomItem part = REGISTRY.get(NamespacedKeyUtils.create(split[0], split[1]));
-            item = part == null ? new EmptyTestableItem() : new TestableStack(part, Integer.parseInt(split[2]));
+            if (part == null) {
+                return new EmptyTestableItem();
+            }
+            item = part;
+            stackAmount = Integer.parseInt(split[2]);
         }
 
+        boolean usingNewStackFormat = false;
+
+        if (args.length >= 2) {
+            try {
+                stackAmount = Integer.parseInt(args[1]);
+                usingNewStackFormat = true;
+            } catch (NumberFormatException ignored) {
+            }
+        }
+
+        // Marked as redundant but i am covering all bases here
         if (item == null || item instanceof EmptyTestableItem) {
             return new EmptyTestableItem();
         }
 
-        String[] enchantArgs = Arrays.copyOfRange(args, 1, args.length);
-
-        Map<Enchantment, Integer> requiredEnchantments = new HashMap<>();
-
-        for (String enchantArg : enchantArgs) {
-            String[] enchantArgSplit = enchantArg.split(":");
-
-            Enchantment enchantment = Enchantment.getByKey(NamespacedKey.minecraft(enchantArgSplit[0].toLowerCase()));
-            int level = Integer.parseInt(enchantArgSplit[1]);
-
-            requiredEnchantments.put(enchantment, level);
-        }
-
-        if (requiredEnchantments.isEmpty()) {
-            return item;
-        }
-
         ItemStack example = item.getItem();
+        ItemMeta meta = example.getItemMeta();
+        assert meta != null;
 
-        if (example.getItemMeta() instanceof EnchantmentStorageMeta storageMeta) {
-            requiredEnchantments.forEach((enchantment, integer) -> storageMeta.addStoredEnchant(enchantment, integer, true));
-            example.setItemMeta(storageMeta);
-        } else {
-            ItemMeta meta = example.getItemMeta();
-            assert meta != null;
-            requiredEnchantments.forEach((enchantment, integer) -> meta.addEnchant(enchantment, integer, true));
-            example.setItemMeta(meta);
+        String[] modifierArgs = Arrays.copyOfRange(args, usingNewStackFormat ? 2 : 1, args.length);
+
+        List<Predicate<ItemStack>> predicates = new ArrayList<>();
+
+        for (LookupArgParser argParser : ARG_PARSERS) {
+            Predicate<ItemStack> predicate = argParser.parseArguments(modifierArgs, meta);
+            if (predicate != null) {
+                predicates.add(argParser.parseArguments(modifierArgs, meta));
+            }
         }
 
-        return new ModifiedTestableItem(
-                item,
-                itemStack -> {
-                    if (!itemStack.hasItemMeta()) {
-                        return false;
-                    }
-
-                    ItemMeta meta = itemStack.getItemMeta();
-
-                    assert meta != null;
-
-                    if (meta instanceof EnchantmentStorageMeta storageMeta) {
-                        for (Map.Entry<Enchantment, Integer> entry : requiredEnchantments.entrySet()) {
-                            if (!storageMeta.hasStoredEnchant(entry.getKey())) {
-                                return false;
-                            }
-                            if (storageMeta.getStoredEnchantLevel(entry.getKey()) < entry.getValue()) {
+        example.setItemMeta(meta);
+        if (!predicates.isEmpty()) {
+            item = new ModifiedTestableItem(
+                    item,
+                    test -> {
+                        for (Predicate<ItemStack> predicate : predicates) {
+                            if (!predicate.test(test)) {
                                 return false;
                             }
                         }
-                    } else {
-                        for (Map.Entry<Enchantment, Integer> entry : requiredEnchantments.entrySet()) {
-                            if (!meta.hasEnchant(entry.getKey())) {
-                                return false;
-                            }
-                            if (meta.getEnchantLevel(entry.getKey()) < entry.getValue()) {
-                                return false;
-                            }
-                        }
-                    }
 
-                    return true;
-                },
-                example
-        );
+                        return true;
+                    },
+                    example
+            );
+        }
+
+        if (stackAmount <= 1) {
+            return item;
+        } else {
+            return new TestableStack(item, stackAmount);
+        }
     }
 
     /**

eco-api/src/main/java/com/willfp/eco/core/items/args/EnchantmentArgParser.java

@@ -0,0 +1,83 @@
+package com.willfp.eco.core.items.args;
+
+import org.bukkit.NamespacedKey;
+import org.bukkit.enchantments.Enchantment;
+import org.bukkit.inventory.ItemStack;
+import org.bukkit.inventory.meta.EnchantmentStorageMeta;
+import org.bukkit.inventory.meta.ItemMeta;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.function.Predicate;
+
+/**
+ * Parses enchantment arguments.
+ */
+public class EnchantmentArgParser implements LookupArgParser {
+    @Override
+    public @Nullable Predicate<ItemStack> parseArguments(@NotNull final String[] args,
+                                                         @NotNull final ItemMeta meta) {
+        Map<Enchantment, Integer> requiredEnchantments = new HashMap<>();
+
+        for (String enchantArg : args) {
+            String[] enchantArgSplit = enchantArg.split(":");
+
+            Enchantment enchantment = Enchantment.getByKey(NamespacedKey.minecraft(enchantArgSplit[0].toLowerCase()));
+            if (enchantment == null) {
+                continue;
+            }
+
+            if (enchantArgSplit.length < 2) {
+                continue;
+            }
+
+            int level = Integer.parseInt(enchantArgSplit[1]);
+
+            requiredEnchantments.put(enchantment, level);
+        }
+
+        if (requiredEnchantments.isEmpty()) {
+            return null;
+        }
+
+        if (meta instanceof EnchantmentStorageMeta storageMeta) {
+            requiredEnchantments.forEach((enchantment, integer) -> storageMeta.addStoredEnchant(enchantment, integer, true));
+        } else {
+            requiredEnchantments.forEach((enchantment, integer) -> meta.addEnchant(enchantment, integer, true));
+        }
+
+        return test -> {
+            if (!test.hasItemMeta()) {
+                return false;
+            }
+
+            ItemMeta testMeta = test.getItemMeta();
+
+            assert testMeta != null;
+
+            if (testMeta instanceof EnchantmentStorageMeta storageMeta) {
+                for (Map.Entry<Enchantment, Integer> entry : requiredEnchantments.entrySet()) {
+                    if (!storageMeta.hasStoredEnchant(entry.getKey())) {
+                        return false;
+                    }
+                    if (storageMeta.getStoredEnchantLevel(entry.getKey()) < entry.getValue()) {
+                        return false;
+                    }
+                }
+            } else {
+                for (Map.Entry<Enchantment, Integer> entry : requiredEnchantments.entrySet()) {
+                    if (!testMeta.hasEnchant(entry.getKey())) {
+                        return false;
+                    }
+                    if (testMeta.getEnchantLevel(entry.getKey()) < entry.getValue()) {
+                        return false;
+                    }
+                }
+            }
+
+            return true;
+        };
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/items/args/LookupArgParser.java

@@ -0,0 +1,25 @@
+package com.willfp.eco.core.items.args;
+
+import com.willfp.eco.core.items.TestableItem;
+import org.bukkit.inventory.ItemStack;
+import org.bukkit.inventory.meta.ItemMeta;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.function.Predicate;
+
+/**
+ * An argument parser should generate the predicate as well
+ * as modify the ItemMeta for {@link TestableItem#getItem()}.
+ */
+public interface LookupArgParser {
+    /**
+     * Parse the arguments.
+     *
+     * @param args The arguments.
+     * @param meta The ItemMeta to modify.
+     * @return The predicate test to apply to the modified item.
+     */
+    @Nullable Predicate<ItemStack> parseArguments(@NotNull String[] args,
+                                                  @NotNull ItemMeta meta);
+}

eco-api/src/main/java/com/willfp/eco/core/items/args/TextureArgParser.java

@@ -0,0 +1,59 @@
+package com.willfp.eco.core.items.args;
+
+import com.willfp.eco.util.SkullUtils;
+import org.bukkit.inventory.ItemStack;
+import org.bukkit.inventory.meta.ItemMeta;
+import org.bukkit.inventory.meta.SkullMeta;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.function.Predicate;
+
+/**
+ * Parse skull textures.
+ */
+public class TextureArgParser implements LookupArgParser {
+    @Override
+    public @Nullable Predicate<ItemStack> parseArguments(@NotNull final String[] args,
+                                                         @NotNull final ItemMeta meta) {
+        String skullTexture = null;
+
+        for (String arg : args) {
+            String[] argSplit = arg.split(":");
+            if (!argSplit[0].equalsIgnoreCase("texture")) {
+                continue;
+            }
+
+            if (argSplit.length < 2) {
+                continue;
+            }
+
+            skullTexture = argSplit[1];
+        }
+
+        if (meta instanceof SkullMeta skullMeta && skullTexture != null) {
+            SkullUtils.setSkullTexture(skullMeta, skullTexture);
+        }
+
+        if (skullTexture == null) {
+            return null;
+        }
+
+        String finalSkullTexture = skullTexture;
+        return test -> {
+            if (!test.hasItemMeta()) {
+                return false;
+            }
+
+            ItemMeta testMeta = test.getItemMeta();
+
+            assert testMeta != null;
+
+            if (testMeta instanceof SkullMeta skullMeta && finalSkullTexture != null) {
+                return finalSkullTexture.equalsIgnoreCase(SkullUtils.getSkullTexture(skullMeta));
+            }
+
+            return true;
+        };
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/recipe/parts/MaterialTestableItem.java

@@ -2,6 +2,7 @@ package com.willfp.eco.core.recipe.parts;
 
 import com.willfp.eco.core.items.TestableItem;
 import lombok.Getter;
+import org.apache.commons.lang.Validate;
 import org.bukkit.Material;
 import org.bukkit.inventory.ItemStack;
 import org.jetbrains.annotations.NotNull;
@@ -23,6 +24,8 @@ public class MaterialTestableItem implements TestableItem {
      * @param material The material.
      */
     public MaterialTestableItem(@NotNull final Material material) {
+        Validate.isTrue(material != Material.AIR, "You can't have air as the type!");
+
         this.material = material;
     }
 

eco-api/src/main/java/com/willfp/eco/core/recipe/parts/ModifiedTestableItem.java

@@ -2,6 +2,7 @@ package com.willfp.eco.core.recipe.parts;
 
 import com.willfp.eco.core.items.TestableItem;
 import lombok.Getter;
+import org.apache.commons.lang.Validate;
 import org.bukkit.inventory.ItemStack;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;

eco-api/src/main/java/com/willfp/eco/core/recipe/parts/TestableStack.java

@@ -1,17 +1,12 @@
 package com.willfp.eco.core.recipe.parts;
 
-import com.willfp.eco.core.Eco;
 import com.willfp.eco.core.items.TestableItem;
 import lombok.Getter;
 import org.apache.commons.lang.Validate;
 import org.bukkit.inventory.ItemStack;
-import org.bukkit.inventory.meta.ItemMeta;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
-import java.util.ArrayList;
-import java.util.List;
-
 /**
  * Stacks of items.
  */
@@ -36,7 +31,8 @@ public class TestableStack implements TestableItem {
      */
     public TestableStack(@NotNull final TestableItem item,
                          final int amount) {
-        Validate.isTrue(!(item instanceof TestableStack));
+        Validate.isTrue(!(item instanceof TestableStack), "You can't stack a stack!");
+        Validate.isTrue(!(item instanceof EmptyTestableItem), "You can't stack air!");
 
         this.handle = item;
         this.amount = amount;
@@ -56,19 +52,7 @@ public class TestableStack implements TestableItem {
     @Override
     public ItemStack getItem() {
         ItemStack temp = handle.getItem().clone();
-        ItemMeta meta = temp.getItemMeta();
-        assert meta != null;
-
-        List<String> lore = meta.hasLore() ? meta.getLore() : new ArrayList<>();
-        assert lore != null;
-        lore.add("");
-        String add = Eco.getHandler().getEcoPlugin().getLangYml().getString("multiple-in-craft");
-        add = add.replace("%amount%", String.valueOf(amount));
-        lore.add(add);
-        meta.setLore(lore);
-        temp.setItemMeta(meta);
         temp.setAmount(amount);
-
         return temp;
     }
 }

eco-api/src/main/java/com/willfp/eco/core/recipe/recipes/ShapedCraftingRecipe.java

@@ -1,16 +1,19 @@
 package com.willfp.eco.core.recipe.recipes;
 
+import com.willfp.eco.core.Eco;
 import com.willfp.eco.core.EcoPlugin;
 import com.willfp.eco.core.PluginDependent;
 import com.willfp.eco.core.items.TestableItem;
 import com.willfp.eco.core.recipe.Recipes;
 import com.willfp.eco.core.recipe.parts.EmptyTestableItem;
+import com.willfp.eco.core.recipe.parts.TestableStack;
 import lombok.Getter;
 import org.bukkit.Bukkit;
 import org.bukkit.NamespacedKey;
 import org.bukkit.inventory.ItemStack;
 import org.bukkit.inventory.RecipeChoice;
 import org.bukkit.inventory.ShapedRecipe;
+import org.bukkit.inventory.meta.ItemMeta;
 import org.jetbrains.annotations.NotNull;
 
 import java.util.ArrayList;
@@ -79,6 +82,10 @@ public final class ShapedCraftingRecipe extends PluginDependent<EcoPlugin> imple
         ShapedRecipe shapedRecipe = new ShapedRecipe(this.getKey(), this.getOutput());
         shapedRecipe.shape("012", "345", "678");
         for (int i = 0; i < 9; i++) {
+            if (parts.get(i) instanceof EmptyTestableItem) {
+                continue;
+            }
+
             char character = String.valueOf(i).toCharArray()[0];
             shapedRecipe.setIngredient(character, parts.get(i).getItem().getType());
         }
@@ -86,8 +93,28 @@ public final class ShapedCraftingRecipe extends PluginDependent<EcoPlugin> imple
         ShapedRecipe displayedRecipe = new ShapedRecipe(this.getDisplayedKey(), this.getOutput());
         displayedRecipe.shape("012", "345", "678");
         for (int i = 0; i < 9; i++) {
+            if (parts.get(i) instanceof EmptyTestableItem) {
+                continue;
+            }
+
             char character = String.valueOf(i).toCharArray()[0];
-            displayedRecipe.setIngredient(character, new RecipeChoice.ExactChoice(parts.get(i).getItem()));
+            ItemStack item = parts.get(i).getItem();
+
+            if (parts.get(i) instanceof TestableStack) {
+                ItemMeta meta = item.getItemMeta();
+                assert meta != null;
+
+                List<String> lore = meta.hasLore() ? meta.getLore() : new ArrayList<>();
+                assert lore != null;
+                lore.add("");
+                String add = Eco.getHandler().getEcoPlugin().getLangYml().getString("multiple-in-craft");
+                add = add.replace("%amount%", String.valueOf(item.getAmount()));
+                lore.add(add);
+                meta.setLore(lore);
+                item.setItemMeta(meta);
+            }
+
+            displayedRecipe.setIngredient(character, new RecipeChoice.ExactChoice(item));
         }
 
         Bukkit.getServer().addRecipe(shapedRecipe);

eco-api/src/main/java/com/willfp/eco/core/requirement/Requirement.java

@@ -0,0 +1,28 @@
+package com.willfp.eco.core.requirement;
+
+import org.bukkit.entity.Player;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.List;
+
+/**
+ * A requirement is a defined goal that a player must meet.
+ */
+public abstract class Requirement {
+    /**
+     * Create a new requirement.
+     */
+    protected Requirement() {
+
+    }
+
+    /**
+     * Test if the player meets the requirement.
+     *
+     * @param player The player.
+     * @param args   The arguments.
+     * @return The requirement.
+     */
+    public abstract boolean doesPlayerMeet(@NotNull Player player,
+                                           @NotNull List<String> args);
+}

eco-api/src/main/java/com/willfp/eco/core/requirement/RequirementFactory.java

@@ -0,0 +1,17 @@
+package com.willfp.eco.core.requirement;
+
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Interface for internal requirement factory implementations.
+ */
+public interface RequirementFactory {
+    /**
+     * Create a requirement.
+     *
+     * @param name The name.
+     * @return The requirement returned for the name.
+     * Will return a requirement that is always true if not found.
+     */
+    Requirement create(@NotNull String name);
+}

eco-api/src/main/java/com/willfp/eco/core/requirement/Requirements.java

@@ -0,0 +1,41 @@
+package com.willfp.eco.core.requirement;
+
+import com.willfp.eco.core.Eco;
+import lombok.experimental.UtilityClass;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Contains methods and fields pertaining to requirements.
+ */
+@UtilityClass
+public class Requirements {
+    /**
+     * Requires a player to have a permission.
+     */
+    public static final Requirement HAS_PERMISSION = Eco.getHandler().getRequirementFactory().create("has-permission");
+
+    /**
+     * Placeholder equals value.
+     */
+    public static final Requirement PLACEHOLDER_EQUALS = Eco.getHandler().getRequirementFactory().create("placeholder-equals");
+
+    /**
+     * Numeric placeholder greater than value.
+     */
+    public static final Requirement PLACEHOLDER_GREATER_THAN = Eco.getHandler().getRequirementFactory().create("placeholder-greater-than");
+
+    /**
+     * Numeric placeholder less than value.
+     */
+    public static final Requirement PLACEHOLDER_LESS_THAN = Eco.getHandler().getRequirementFactory().create("placeholder-less-than");
+
+    /**
+     * Get Requirements matching ID.
+     *
+     * @param name The ID to search for.
+     * @return The matching Requirements.
+     */
+    public static Requirement getByID(@NotNull final String name) {
+        return Eco.getHandler().getRequirementFactory().create(name);
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/tuples/Pair.java

@@ -38,4 +38,26 @@ public class Pair<A, B> {
         this.first = first;
         this.second = second;
     }
+
+    /**
+     * component1 exists to allow a pair to be destructured by kotlin.
+     * The default kotlin pair already has this, however there is no default
+     * pair in java so this exists for parity.
+     *
+     * @return First.
+     */
+    public A component1() {
+        return first;
+    }
+
+    /**
+     * component2 exists to allow a pair to be destructured by kotlin.
+     * The default kotlin pair already has this, however there is no default
+     * pair in java so this exists for parity.
+     *
+     * @return First.
+     */
+    public B component2() {
+        return second;
+    }
 }

eco-api/src/main/java/com/willfp/eco/core/tuples/Triplet.java

@@ -34,4 +34,15 @@ public class Triplet<A, B, C> extends Pair<A, B> {
 
         this.third = third;
     }
+
+    /**
+     * component3 exists to allow a pair to be destructured by kotlin.
+     * The default kotlin pair already has this, however there is no default
+     * pair in java so this exists for parity.
+     *
+     * @return First.
+     */
+    public C component3() {
+        return third;
+    }
 }

eco-api/src/main/java/com/willfp/eco/util/ArrowUtils.java

@@ -19,7 +19,7 @@ public class ArrowUtils {
      * Get the bow from an arrow.
      *
      * @param arrow The arrow.
-     * @return The bow.
+     * @return The bow, or null if no bow.
      */
     @Nullable
     public ItemStack getBow(@NotNull final Arrow arrow) {

eco-api/src/main/java/com/willfp/eco/util/BlockUtils.java

@@ -63,6 +63,7 @@ public class BlockUtils {
      * @param limit            The maximum size of vein to return.
      * @return A set of all {@link Block}s.
      */
+    @NotNull
     public Set<Block> getVein(@NotNull final Block start,
                               @NotNull final List<Material> allowedMaterials,
                               final int limit) {

eco-api/src/main/java/com/willfp/eco/util/LightningUtils.java

@@ -2,6 +2,7 @@ package com.willfp.eco.util;
 
 import lombok.experimental.UtilityClass;
 import org.bukkit.Location;
+import org.bukkit.Sound;
 import org.bukkit.entity.LivingEntity;
 import org.jetbrains.annotations.NotNull;
 
@@ -10,18 +11,37 @@ import org.jetbrains.annotations.NotNull;
  */
 @UtilityClass
 public class LightningUtils {
+
     /**
      * Strike lightning on player without fire.
      *
      * @param victim The entity to smite.
      * @param damage The damage to deal.
+     * @param silent If the lightning sound should be played locally
+     */
+    public void strike(@NotNull final LivingEntity victim,
+                       final double damage,
+                       final boolean silent) {
+        Location loc = victim.getLocation();
+
+        if (silent) {
+            victim.getWorld().spigot().strikeLightningEffect(loc, true);
+            victim.getWorld().playSound(loc, Sound.ENTITY_LIGHTNING_BOLT_IMPACT, 1, 1);
+        } else {
+            victim.getWorld().strikeLightningEffect(loc);
+        }
+
+        victim.damage(damage);
+    }
+
+    /**
+     * Strike lightning on a victim without fire.
+     *
+     * @param victim The entity to smite.
+     * @param damage The damage to deal.
      */
     public void strike(@NotNull final LivingEntity victim,
                        final double damage) {
-        Location loc = victim.getLocation();
-
-        victim.getWorld().strikeLightningEffect(loc);
-
-        victim.damage(damage);
+        strike(victim, damage, false);
     }
 }

eco-api/src/main/java/com/willfp/eco/util/ListUtils.java

@@ -1,6 +1,8 @@
 package com.willfp.eco.util;
 
 import lombok.experimental.UtilityClass;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 import java.util.ArrayList;
 import java.util.List;
@@ -18,8 +20,9 @@ public class ListUtils {
      * @param <T>     The type of the object stored in the list.
      * @return The list, filled will null objects.
      */
-    public <T> List<List<T>> create2DList(final int rows,
-                                          final int columns) {
+    @NotNull
+    public <@Nullable T> List<List<T>> create2DList(final int rows,
+                                                    final int columns) {
         List<List<T>> list = new ArrayList<>(rows);
         while (list.size() < rows) {
             List<T> row = new ArrayList<>(columns);

eco-api/src/main/java/com/willfp/eco/util/MenuUtils.java

@@ -2,6 +2,7 @@ package com.willfp.eco.util;
 
 import com.willfp.eco.core.tuples.Pair;
 import lombok.experimental.UtilityClass;
+import org.jetbrains.annotations.NotNull;
 
 /**
  * Utilities / API methods for menus.
@@ -14,6 +15,7 @@ public class MenuUtils {
      * @param slot The slot.
      * @return The pair of row and columns.
      */
+    @NotNull
     public Pair<Integer, Integer> convertSlotToRowColumn(final int slot) {
         int row = Math.floorDiv(slot, 9);
         int column = slot - row * 9;

eco-api/src/main/java/com/willfp/eco/util/NamespacedKeyUtils.java

@@ -17,6 +17,7 @@ public class NamespacedKeyUtils {
      * @param string The string.
      * @return The key.
      */
+    @NotNull
     public NamespacedKey createEcoKey(@NotNull final String string) {
         return Objects.requireNonNull(NamespacedKey.fromString("eco:" + string));
     }
@@ -28,6 +29,7 @@ public class NamespacedKeyUtils {
      * @param key       The key.
      * @return The key.
      */
+    @NotNull
     public NamespacedKey create(@NotNull final String namespace,
                                 @NotNull final String key) {
         return Objects.requireNonNull(NamespacedKey.fromString(namespace + ":" + key));

eco-api/src/main/java/com/willfp/eco/util/NumberUtils.java

@@ -1,5 +1,6 @@
 package com.willfp.eco.util;
 
+import lombok.experimental.NonFinal;
 import lombok.experimental.UtilityClass;
 import org.jetbrains.annotations.NotNull;
 
@@ -109,6 +110,7 @@ public class NumberUtils {
      * @param number The number to convert.
      * @return The number, converted to a roman numeral.
      */
+    @NotNull
     public String toNumeral(final int number) {
         if (number >= 1 && number <= 4096) {
             int l = NUMERALS.floorKey(number);
@@ -199,6 +201,7 @@ public class NumberUtils {
      * @param toFormat The number to format.
      * @return Formatted.
      */
+    @NotNull
     public String format(final double toFormat) {
         DecimalFormat df = new DecimalFormat("0.00");
         String formatted = df.format(toFormat);

eco-api/src/main/java/com/willfp/eco/util/SkullUtils.java

@@ -5,8 +5,10 @@ import org.apache.commons.lang.Validate;
 import org.bukkit.inventory.meta.SkullMeta;
 import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 import java.util.function.BiConsumer;
+import java.util.function.Function;
 
 /**
  * Utilities / API methods for player heads.
@@ -23,6 +25,11 @@ public class SkullUtils {
      */
     private BiConsumer<SkullMeta, String> metaSetConsumer = null;
 
+    /**
+     * The meta get function.
+     */
+    private Function<SkullMeta, String> metaGetConsumer = null;
+
     /**
      * Set the texture of a skull from base64.
      *
@@ -37,16 +44,33 @@ public class SkullUtils {
         metaSetConsumer.accept(meta, base64);
     }
 
+    /**
+     * Get the texture of a skull - in base64.
+     *
+     * @param meta The meta to modify.
+     * @return The texture, potentially null.
+     */
+    @Nullable
+    public String getSkullTexture(@NotNull final SkullMeta meta) {
+        Validate.isTrue(initialized, "Must be initialized!");
+        Validate.notNull(metaGetConsumer, "Must be initialized!");
+
+        return metaGetConsumer.apply(meta);
+    }
+
     /**
      * Initialize the skull texture function.
      *
-     * @param function The function.
+     * @param function  The function.
+     * @param function2 Get function.
      */
     @ApiStatus.Internal
-    public void initialize(@NotNull final BiConsumer<SkullMeta, String> function) {
+    public void initialize(@NotNull final BiConsumer<SkullMeta, String> function,
+                           @NotNull final Function<SkullMeta, String> function2) {
         Validate.isTrue(!initialized, "Already initialized!");
 
         metaSetConsumer = function;
+        metaGetConsumer = function2;
         initialized = true;
     }
 }

eco-api/src/main/java/com/willfp/eco/util/StringUtils.java

@@ -64,6 +64,7 @@ public class StringUtils {
      * @param list The messages to format.
      * @return The message, formatted.
      */
+    @NotNull
     public List<String> formatList(@NotNull final List<String> list) {
         return formatList(list, (Player) null);
     }
@@ -77,6 +78,7 @@ public class StringUtils {
      * @param player The player to translate placeholders with respect to.
      * @return The message, format.
      */
+    @NotNull
     public List<String> formatList(@NotNull final List<String> list,
                                    @Nullable final Player player) {
         return formatList(list, player, FormatOption.WITH_PLACEHOLDERS);
@@ -91,6 +93,7 @@ public class StringUtils {
      * @param option The format option.
      * @return The message, formatted.
      */
+    @NotNull
     public List<String> formatList(@NotNull final List<String> list,
                                    @NotNull final FormatOption option) {
         return formatList(list, null, option);
@@ -106,6 +109,7 @@ public class StringUtils {
      * @param option The options.
      * @return The message, format.
      */
+    @NotNull
     public List<String> formatList(@NotNull final List<String> list,
                                    @Nullable final Player player,
                                    @NotNull final FormatOption option) {
@@ -126,6 +130,7 @@ public class StringUtils {
      * @return The message, formatted.
      * @see StringUtils#format(String, Player)
      */
+    @NotNull
     public String format(@NotNull final String message) {
         return format(message, (Player) null);
     }
@@ -139,6 +144,7 @@ public class StringUtils {
      * @param player  The player to translate placeholders with respect to.
      * @return The message, formatted.
      */
+    @NotNull
     public String format(@NotNull final String message,
                          @Nullable final Player player) {
         return format(message, player, FormatOption.WITH_PLACEHOLDERS);
@@ -154,6 +160,7 @@ public class StringUtils {
      * @return The message, formatted.
      * @see StringUtils#format(String, Player)
      */
+    @NotNull
     public String format(@NotNull final String message,
                          @NotNull final FormatOption option) {
         return format(message, null, option);
@@ -169,6 +176,7 @@ public class StringUtils {
      * @param option  The format options.
      * @return The message, formatted.
      */
+    @NotNull
     public String format(@NotNull final String message,
                          @Nullable final Player player,
                          @NotNull final FormatOption option) {
@@ -284,6 +292,7 @@ public class StringUtils {
      * @param object The object to convert to string.
      * @return The object stringified.
      */
+    @NotNull
     public String internalToString(@Nullable final Object object) {
         if (object == null) {
             return "null";
@@ -309,6 +318,7 @@ public class StringUtils {
      * @param prefix The substring to remove.
      * @return The string with the prefix removed.
      */
+    @NotNull
     public String removePrefix(@NotNull final String string,
                                @NotNull final String prefix) {
         if (string.startsWith(prefix)) {
@@ -323,6 +333,7 @@ public class StringUtils {
      * @param legacy The legacy string.
      * @return The JSON String.
      */
+    @NotNull
     public String legacyToJson(@NotNull final String legacy) {
         return GsonComponentSerializer.gson().serialize(
                 Component.empty().decoration(TextDecoration.ITALIC, false).append(
@@ -337,6 +348,7 @@ public class StringUtils {
      * @param json The JSON string.
      * @return The legacy string.
      */
+    @NotNull
     public String jsonToLegacy(@NotNull final String json) {
         return LEGACY_COMPONENT_SERIALIZER.serialize(
                 GsonComponentSerializer.gson().deserialize(json)

eco-api/src/main/java/com/willfp/eco/util/TeamUtils.java

@@ -43,6 +43,7 @@ public class TeamUtils {
      * @param color The color to find the team for.
      * @return The team.
      */
+    @NotNull
     public Team fromChatColor(@NotNull final ChatColor color) {
         if (CHAT_COLOR_TEAMS.containsKey(color)) {
             return CHAT_COLOR_TEAMS.get(color);
@@ -70,6 +71,7 @@ public class TeamUtils {
      * @param material The material to find the team from.
      * @return The team.
      */
+    @NotNull
     public Team getMaterialColorTeam(@NotNull final Material material) {
         return fromChatColor(MATERIAL_COLORS.getOrDefault(material, ChatColor.WHITE));
     }

eco-api/src/main/java/com/willfp/eco/util/VectorUtils.java

@@ -44,6 +44,7 @@ public class VectorUtils {
      * @param vec The vector to simplify.
      * @return The vector, simplified.
      */
+    @NotNull
     public Vector simplifyVector(@NotNull final Vector vec) {
         double x = Math.abs(vec.getX());
         double y = Math.abs(vec.getY());
@@ -76,6 +77,7 @@ public class VectorUtils {
      * @param radius The radius.
      * @return An array of {@link Vector}s.
      */
+    @NotNull
     public Vector[] getCircle(final int radius) {
         Vector[] cached = CIRCLE_CACHE.get(radius);
         if (cached != null) {
@@ -112,6 +114,7 @@ public class VectorUtils {
      * @param radius The radius of the square.
      * @return An array of {@link Vector}s.
      */
+    @NotNull
     public Vector[] getSquare(final int radius) {
         List<Vector> vectors = new ArrayList<>();
 
@@ -136,6 +139,7 @@ public class VectorUtils {
      * @param radius The radius of the cube.
      * @return An array of {@link Vector}s.
      */
+    @NotNull
     public Vector[] getCube(final int radius) {
         List<Vector> vectors = new ArrayList<>();
 

eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/config/EcoConfigFactory.kt

@@ -6,6 +6,7 @@ import com.willfp.eco.core.config.interfaces.JSONConfig
 import com.willfp.eco.core.config.wrapper.ConfigFactory
 import com.willfp.eco.internal.config.json.EcoJSONConfigSection
 import com.willfp.eco.internal.config.json.EcoLoadableJSONConfig
+import com.willfp.eco.internal.config.json.EcoUpdatableJSONConfig
 import com.willfp.eco.internal.config.yaml.EcoLoadableYamlConfig
 import com.willfp.eco.internal.config.yaml.EcoUpdatableYamlConfig
 import com.willfp.eco.internal.config.yaml.EcoYamlConfigSection
@@ -30,6 +31,24 @@ class EcoConfigFactory : ConfigFactory {
         )
     }
 
+    override fun createUpdatableJSONConfig(
+        configName: String,
+        plugin: EcoPlugin,
+        subDirectoryPath: String,
+        source: Class<*>,
+        removeUnused: Boolean,
+        vararg updateBlacklist: String
+    ): JSONConfig {
+        return EcoUpdatableJSONConfig(
+            configName,
+            plugin,
+            subDirectoryPath,
+            source,
+            removeUnused,
+            *updateBlacklist
+        )
+    }
+
     override fun createLoadableJSONConfig(
         configName: String,
         plugin: EcoPlugin,

eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/config/json/EcoLoadableJSONConfig.kt

@@ -8,11 +8,11 @@ import java.nio.file.Files
 import java.nio.file.StandardOpenOption
 
 @Suppress("UNCHECKED_CAST")
-class EcoLoadableJSONConfig(
+open class EcoLoadableJSONConfig(
     configName: String,
     private val plugin: EcoPlugin,
     private val subDirectoryPath: String,
-    private val source: Class<*>
+    val source: Class<*>
 ) : EcoJSONConfigWrapper(), LoadableConfig {
 
     private val configFile: File
@@ -65,7 +65,7 @@ class EcoLoadableJSONConfig(
 
     @Throws(FileNotFoundException::class)
     fun init(file: File) {
-        super.init(handle.fromJson(FileReader(file), Map::class.java) as @NotNull MutableMap<String, Any>)
+        super.init(handle.fromJson(FileReader(file), Map::class.java) as MutableMap<String, Any>)
     }
 
     override fun getName(): String {

eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/config/json/EcoUpdatableJSONConfig.kt

@@ -0,0 +1,74 @@
+package com.willfp.eco.internal.config.json
+
+import com.willfp.eco.core.EcoPlugin
+import org.bukkit.configuration.InvalidConfigurationException
+import org.bukkit.configuration.file.YamlConfiguration
+import java.io.BufferedReader
+import java.io.IOException
+import java.io.InputStreamReader
+import java.nio.charset.StandardCharsets
+
+open class EcoUpdatableJSONConfig(
+    configName: String,
+    plugin: EcoPlugin,
+    subDirectoryPath: String,
+    source: Class<*>,
+    private val removeUnused: Boolean,
+    vararg updateBlacklist: String
+) : EcoLoadableJSONConfig(configName, plugin, subDirectoryPath, source) {
+
+    private val updateBlacklist: MutableList<String> = mutableListOf(*updateBlacklist)
+
+    fun update() {
+        super.clearCache()
+        try {
+            this.init(configFile)
+            val newConfig = configInJar
+            if (newConfig.getKeys(true) == this.getKeys(true)) {
+                return
+            }
+            newConfig.getKeys(true).forEach { key: String ->
+                if (!this.getKeys(true).contains(key)) {
+                    if (updateBlacklist.stream().noneMatch { s: String -> key.contains(s) }) {
+                        this.set(key, newConfig[key])
+                    }
+                }
+            }
+            if (removeUnused) {
+                this.getKeys(true).forEach { s ->
+                    if (!newConfig.getKeys(true).contains(s)) {
+                        if (updateBlacklist.stream().noneMatch(s::contains)) {
+                            this.set(s, null)
+                        }
+                    }
+                }
+            }
+            this.save()
+        } catch (e: IOException) {
+            e.printStackTrace()
+        } catch (e: InvalidConfigurationException) {
+            e.printStackTrace()
+        }
+    }
+
+    private val configInJar: YamlConfiguration
+        get() {
+            val newIn = this.source.getResourceAsStream(resourcePath) ?: throw NullPointerException("$name is null?")
+            val reader = BufferedReader(InputStreamReader(newIn, StandardCharsets.UTF_8))
+            val newConfig = YamlConfiguration()
+            try {
+                newConfig.load(reader)
+            } catch (e: IOException) {
+                e.printStackTrace()
+            } catch (e: InvalidConfigurationException) {
+                e.printStackTrace()
+            }
+            return newConfig
+        }
+
+    init {
+        this.updateBlacklist.removeIf { obj: String -> obj.isEmpty() }
+        plugin.configHandler.addConfig(this)
+        update()
+    }
+}

eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/config/updating/EcoConfigHandler.kt

@@ -5,6 +5,7 @@ import com.willfp.eco.core.config.interfaces.LoadableConfig
 import com.willfp.eco.core.config.updating.ConfigHandler
 import com.willfp.eco.core.config.updating.ConfigUpdater
 import com.willfp.eco.internal.config.json.EcoLoadableJSONConfig
+import com.willfp.eco.internal.config.json.EcoUpdatableJSONConfig
 import com.willfp.eco.internal.config.updating.exceptions.InvalidUpdateMethodException
 import com.willfp.eco.internal.config.yaml.EcoLoadableYamlConfig
 import com.willfp.eco.internal.config.yaml.EcoUpdatableYamlConfig
@@ -55,6 +56,7 @@ class EcoConfigHandler(
         for (config in configs) {
             when (config) {
                 is EcoUpdatableYamlConfig -> config.update()
+                is EcoUpdatableJSONConfig -> config.update()
                 is EcoLoadableYamlConfig -> config.reloadFromFile()
                 is EcoLoadableJSONConfig -> config.reloadFromFile()
             }

eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/display/EcoDisplayHandler.kt

@@ -0,0 +1,119 @@
+package com.willfp.eco.internal.display
+
+import com.willfp.eco.core.EcoPlugin
+import com.willfp.eco.core.display.Display
+import com.willfp.eco.core.display.DisplayHandler
+import com.willfp.eco.core.display.DisplayModule
+import com.willfp.eco.core.display.DisplayPriority
+import com.willfp.eco.core.fast.FastItemStack
+import org.bukkit.NamespacedKey
+import org.bukkit.entity.Player
+import org.bukkit.inventory.ItemStack
+import org.bukkit.persistence.PersistentDataType
+
+class EcoDisplayHandler(plugin: EcoPlugin) : DisplayHandler {
+    /**
+     * All registered display modules.
+     */
+    private val registeredModules = mutableMapOf<DisplayPriority, MutableList<DisplayModule>>()
+
+    /**
+     * NamespacedKey for finalizing.
+     */
+    private val finalizeKey: NamespacedKey = plugin.namespacedKeyFactory.create("finalized")
+
+    init {
+        for (priority in DisplayPriority.values()) {
+            registeredModules[priority] = mutableListOf()
+        }
+    }
+
+    override fun registerDisplayModule(module: DisplayModule) {
+        val modules = registeredModules[module.priority] ?: return
+        modules.removeIf { module1: DisplayModule ->
+            module1.pluginName.equals(module.pluginName, ignoreCase = true)
+        }
+        modules.add(module)
+        registeredModules[module.priority] = modules
+    }
+
+    override fun display(itemStack: ItemStack, player: Player?): ItemStack {
+        val pluginVarArgs = mutableMapOf<String, Array<Any>>()
+
+        for (priority in DisplayPriority.values()) {
+            val modules = registeredModules[priority] ?: continue
+            for (module in modules) {
+                pluginVarArgs[module.pluginName] = module.generateVarArgs(itemStack)
+            }
+        }
+
+        Display.revert(itemStack)
+
+        itemStack.itemMeta ?: return itemStack
+
+        for (priority in DisplayPriority.values()) {
+            val modules = registeredModules[priority] ?: continue
+            for (module in modules) {
+                val varargs = pluginVarArgs[module.pluginName] ?: continue
+                Display.callDisplayModule(module, itemStack, player, *varargs)
+            }
+        }
+
+        return itemStack
+    }
+
+    override fun revert(itemStack: ItemStack): ItemStack {
+        if (Display.isFinalized(itemStack)) {
+            Display.unfinalize(itemStack)
+        }
+
+        val fast = FastItemStack.wrap(itemStack)
+        val lore = fast.lore
+
+        if (lore.isNotEmpty() && lore.removeIf { line: String ->
+                line.startsWith(
+                    Display.PREFIX
+                )
+            }) { // Only modify lore if needed.
+            fast.lore = lore
+        }
+
+        for (priority in DisplayPriority.values()) {
+            val modules = registeredModules[priority] ?: continue
+            for (module in modules) {
+                module.revert(itemStack)
+            }
+        }
+
+        return itemStack
+    }
+
+    override fun finalize(itemStack: ItemStack): ItemStack {
+        if (itemStack.type.maxStackSize > 1) {
+            return itemStack
+        }
+
+        val meta = itemStack.itemMeta ?: return itemStack
+
+        val container = meta.persistentDataContainer
+        container.set(finalizeKey, PersistentDataType.INTEGER, 1)
+        itemStack.itemMeta = meta
+        return itemStack
+    }
+
+    override fun unfinalize(itemStack: ItemStack): ItemStack {
+        val meta = itemStack.itemMeta ?: return itemStack
+
+        val container = meta.persistentDataContainer
+        container.remove(finalizeKey)
+        itemStack.itemMeta = meta
+        return itemStack
+    }
+
+    override fun isFinalized(itemStack: ItemStack): Boolean {
+        val meta = itemStack.itemMeta ?: return false
+
+        val container = meta.persistentDataContainer
+        return container.has(finalizeKey, PersistentDataType.INTEGER)
+    }
+}

eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/events/EcoEventManager.kt

@@ -6,7 +6,7 @@ import org.bukkit.Bukkit
 import org.bukkit.event.HandlerList
 import org.bukkit.event.Listener
 
-class EcoEventManager constructor(private val plugin: EcoPlugin) : EventManager {
+class EcoEventManager (private val plugin: EcoPlugin) : EventManager {
     override fun registerListener(listener: Listener) {
         Bukkit.getPluginManager().registerEvents(listener, plugin)
     }

eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/gui/menu/EcoMenu.kt

@@ -63,6 +63,7 @@ class EcoMenu(
 
     fun handleClose(event: InventoryCloseEvent) {
         onClose.handle(event, this)
+        MenuHandler.unregisterMenu(event.inventory)
     }
 
     override fun getRows(): Int {

eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/gui/slot/EcoCaptivatorSlot.kt

@@ -15,7 +15,7 @@ class EcoCaptivatorSlot : EcoSlot(
     { _, _, _ -> }
 ) {
     companion object {
-        val plugin = Eco.getHandler().ecoPlugin!!
+        val plugin = Eco.getHandler().ecoPlugin
 
         val allowMovingItem = SlotHandler { event, _, _ ->
             event.isCancelled = false

eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/requirement/EcoRequirementFactory.kt

@@ -0,0 +1,17 @@
+package com.willfp.eco.internal.requirement
+
+import com.willfp.eco.core.requirement.Requirement
+import com.willfp.eco.core.requirement.RequirementFactory
+import com.willfp.eco.internal.requirement.requirements.*
+
+class EcoRequirementFactory: RequirementFactory {
+    override fun create(name: String): Requirement {
+        return when (name.lowercase()) {
+            "has-permission" -> RequirementHasPermission()
+            "placeholder-equals" -> RequirementPlaceholderEquals()
+            "placeholder-greater-than" -> RequirementPlaceholderGreaterThan()
+            "placeholder-less-than" -> RequirementPlaceholderLessThan()
+            else -> RequirementTrue()
+        }
+    }
+}

eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/requirement/requirements/RequirementHasPermission.kt

@@ -0,0 +1,18 @@
+package com.willfp.eco.internal.requirement.requirements
+
+import com.willfp.eco.core.requirement.Requirement
+import org.bukkit.entity.Player
+
+class RequirementHasPermission : Requirement() {
+    override fun doesPlayerMeet(
+        player: Player,
+        args: List<String>
+    ): Boolean {
+        if (args.isEmpty()) {
+            return false
+        }
+
+        val permission = args[0]
+        return player.hasPermission(permission)
+    }
+}

eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/requirement/requirements/RequirementPlaceholderEquals.kt

@@ -0,0 +1,20 @@
+package com.willfp.eco.internal.requirement.requirements
+
+import com.willfp.eco.core.integrations.placeholder.PlaceholderManager
+import com.willfp.eco.core.requirement.Requirement
+import org.bukkit.entity.Player
+
+class RequirementPlaceholderEquals : Requirement() {
+    override fun doesPlayerMeet(
+        player: Player,
+        args: List<String>
+    ): Boolean {
+        if (args.size < 2) {
+            return false
+        }
+
+        val placeholder = args[0]
+        val equals = args[1]
+        return PlaceholderManager.translatePlaceholders(placeholder, player).equals(equals, ignoreCase = true)
+    }
+}

eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/requirement/requirements/RequirementPlaceholderGreaterThan.kt

@@ -0,0 +1,20 @@
+package com.willfp.eco.internal.requirement.requirements
+
+import com.willfp.eco.core.integrations.placeholder.PlaceholderManager
+import com.willfp.eco.core.requirement.Requirement
+import org.bukkit.entity.Player
+
+class RequirementPlaceholderGreaterThan : Requirement() {
+    override fun doesPlayerMeet(
+        player: Player,
+        args: List<String>
+    ): Boolean {
+        if (args.size < 2) {
+            return false
+        }
+
+        val placeholder = args[0]
+        val equals = args[1].toDoubleOrNull() ?: return false
+        return PlaceholderManager.translatePlaceholders(placeholder, player).toDoubleOrNull() ?: 0.0 >= equals
+    }
+}

eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/requirement/requirements/RequirementPlaceholderLessThan.kt

@@ -0,0 +1,20 @@
+package com.willfp.eco.internal.requirement.requirements
+
+import com.willfp.eco.core.integrations.placeholder.PlaceholderManager
+import com.willfp.eco.core.requirement.Requirement
+import org.bukkit.entity.Player
+
+class RequirementPlaceholderLessThan : Requirement() {
+    override fun doesPlayerMeet(
+        player: Player,
+        args: List<String>
+    ): Boolean {
+        if (args.size < 2) {
+            return false
+        }
+
+        val placeholder = args[0]
+        val equals = args[1].toDoubleOrNull() ?: return false
+        return PlaceholderManager.translatePlaceholders(placeholder, player).toDoubleOrNull() ?: 0.0 < equals
+    }
+}

eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/requirement/requirements/RequirementTrue.kt

@@ -0,0 +1,13 @@
+package com.willfp.eco.internal.requirement.requirements
+
+import com.willfp.eco.core.requirement.Requirement
+import org.bukkit.entity.Player
+
+class RequirementTrue : Requirement() {
+    override fun doesPlayerMeet(
+        player: Player,
+        args: List<String>
+    ): Boolean {
+        return true
+    }
+}

eco-core/core-nms/v1_16_R3/src/main/kotlin/com/willfp/eco/proxy/v1_16_R3/Skull.kt

@@ -1,32 +1,43 @@
 package com.willfp.eco.proxy.v1_16_R3
+
 import com.mojang.authlib.GameProfile
 import com.mojang.authlib.properties.Property
-import org.bukkit.inventory.meta.SkullMeta
 import com.willfp.eco.proxy.SkullProxy
+import org.bukkit.inventory.meta.SkullMeta
+import java.lang.reflect.Field
 import java.lang.reflect.Method
 import java.util.*
 
 class Skull : SkullProxy {
     private lateinit var setProfile: Method
+    private lateinit var profile: Field
 
     override fun setSkullTexture(
         meta: SkullMeta,
         base64: String
     ) {
-        try {
-            if (!this::setProfile.isInitialized) {
-                setProfile = meta.javaClass.getDeclaredMethod("setProfile", GameProfile::class.java)
-                setProfile.isAccessible = true
-            }
-            val uuid = UUID(
-                base64.substring(base64.length - 20).hashCode().toLong(),
-                base64.substring(base64.length - 10).hashCode().toLong()
-            )
-            val profile = GameProfile(uuid, "eco")
-            profile.properties.put("textures", Property("textures", base64))
-            setProfile.invoke(meta, profile)
-        } catch (e: ReflectiveOperationException) {
-            e.printStackTrace()
+        if (!this::setProfile.isInitialized) {
+            setProfile = meta.javaClass.getDeclaredMethod("setProfile", GameProfile::class.java)
+            setProfile.isAccessible = true
         }
+        val uuid = UUID(
+            base64.substring(base64.length - 20).hashCode().toLong(),
+            base64.substring(base64.length - 10).hashCode().toLong()
+        )
+        val profile = GameProfile(uuid, "eco")
+        profile.properties.put("textures", Property("textures", base64))
+        setProfile.invoke(meta, profile)
+    }
+
+    override fun getSkullTexture(
+        meta: SkullMeta
+    ): String? {
+        if (!this::profile.isInitialized) {
+            profile = meta.javaClass.getDeclaredField("profile")
+            profile.isAccessible = true
+        }
+        val profile = profile[meta] as GameProfile?
+        val property = profile?.properties?.get("textures") as Property?
+        return property?.value
     }
 }

eco-core/core-nms/v1_17_R1/src/main/kotlin/com/willfp/eco/proxy/v1_17_R1/Skull.kt

@@ -4,30 +4,40 @@ import com.mojang.authlib.GameProfile
 import com.mojang.authlib.properties.Property
 import com.willfp.eco.proxy.SkullProxy
 import org.bukkit.inventory.meta.SkullMeta
+import java.lang.reflect.Field
 import java.lang.reflect.Method
 import java.util.*
 
 class Skull : SkullProxy {
     private lateinit var setProfile: Method
+    private lateinit var profile: Field
 
     override fun setSkullTexture(
         meta: SkullMeta,
         base64: String
     ) {
-        try {
-            if (!this::setProfile.isInitialized) {
-                setProfile = meta.javaClass.getDeclaredMethod("setProfile", GameProfile::class.java)
-                setProfile.isAccessible = true
-            }
-            val uuid = UUID(
-                base64.substring(base64.length - 20).hashCode().toLong(),
-                base64.substring(base64.length - 10).hashCode().toLong()
-            )
-            val profile = GameProfile(uuid, "eco")
-            profile.properties.put("textures", Property("textures", base64))
-            setProfile.invoke(meta, profile)
-        } catch (e: ReflectiveOperationException) {
-            e.printStackTrace()
+        if (!this::setProfile.isInitialized) {
+            setProfile = meta.javaClass.getDeclaredMethod("setProfile", GameProfile::class.java)
+            setProfile.isAccessible = true
         }
+        val uuid = UUID(
+            base64.substring(base64.length - 20).hashCode().toLong(),
+            base64.substring(base64.length - 10).hashCode().toLong()
+        )
+        val profile = GameProfile(uuid, "eco")
+        profile.properties.put("textures", Property("textures", base64))
+        setProfile.invoke(meta, profile)
+    }
+
+    override fun getSkullTexture(
+        meta: SkullMeta
+    ): String? {
+        if (!this::profile.isInitialized) {
+            profile = meta.javaClass.getDeclaredField("profile")
+            profile.isAccessible = true
+        }
+        val profile = profile[meta] as GameProfile?
+        val property = profile?.properties?.get("textures") as Property?
+        return property?.value
     }
 }

eco-core/core-plugin/build.gradle

@@ -21,8 +21,8 @@ dependencies {
     compileOnly 'me.clip:placeholderapi:2.10.9'
     compileOnly 'com.willfp:Oraxen:e1f4003d8d'
     compileOnly 'com.github.brcdev-minecraft:shopgui-api:2.2.0'
-
-    compileOnly 'com.github.LoneDev6:API-ItemsAdder:2.3.8'
+    compileOnly 'com.github.LoneDev6:API-ItemsAdder:2.4.7'
+    compileOnly 'me.arcaniax:HeadDatabase-API:1.2.0'
 
     // CombatLogX V10 + NewbieHelper Expansion
     compileOnly 'com.SirBlobman.combatlogx:CombatLogX-API:10.0.0.0-SNAPSHOT'

eco-core/core-plugin/src/main/java/com/willfp/eco/spigot/recipes/ShapedRecipeListener.java

@@ -98,16 +98,65 @@ public class ShapedRecipeListener extends PluginDependent<EcoPlugin> implements
             return;
         }
 
-        this.getPlugin().getScheduler().runLater(() -> {
-            for (int i = 0; i < 9; i++) {
-                ItemStack inMatrix = event.getInventory().getMatrix()[i];
-                TestableItem inRecipe = matched.getParts().get(i);
+        boolean isStackedRecipe = false;
 
-                if (inRecipe instanceof TestableStack testableStack) {
+        int upperBound = 64;
+        for (int i = 0; i < 9; i++) {
+            ItemStack inMatrix = event.getInventory().getMatrix()[i];
+            TestableItem inRecipe = matched.getParts().get(i);
+
+            if (inRecipe instanceof TestableStack testableStack) {
+                int max = Math.floorDiv(inMatrix.getAmount(), testableStack.getAmount());
+                if (max < upperBound) {
+                    upperBound = max;
+                }
+                isStackedRecipe = true;
+            } else if (inMatrix != null) {
+                int max = inMatrix.getAmount();
+                if (max < upperBound) {
+                    upperBound = max;
+                }
+            }
+        }
+
+        if (!isStackedRecipe) {
+            return;
+        }
+
+        int toGivePerRecipe = event.getRecipe().getResult().getAmount();
+        int maxStackSize = event.getRecipe().getResult().getMaxStackSize();
+        while (toGivePerRecipe * upperBound > maxStackSize) {
+            upperBound--;
+        }
+
+        for (int i = 0; i < 9; i++) {
+            ItemStack inMatrix = event.getInventory().getMatrix()[i];
+            TestableItem inRecipe = matched.getParts().get(i);
+
+            if (inRecipe instanceof TestableStack testableStack) {
+                if (event.isShiftClick()) {
+                    int amount = inMatrix.getAmount() + 1;
+                    for (int j = 0; j < upperBound; j++) {
+                        amount -= testableStack.getAmount();
+                    }
+                    inMatrix.setAmount(amount);
+                } else {
                     inMatrix.setAmount(inMatrix.getAmount() - (testableStack.getAmount() - 1));
                 }
             }
-        }, 1);
+        }
+
+        int finalUpperBound = upperBound;
+
+        if (event.isShiftClick()) {
+            ItemStack result = event.getInventory().getResult();
+            if (result == null) {
+                return;
+            }
+
+            result.setAmount(result.getAmount() * finalUpperBound);
+            event.getInventory().setResult(result);
+        }
     }
 
     @EventHandler

eco-core/core-plugin/src/main/kotlin/com/willfp/eco/spigot/EcoHandler.kt

@@ -15,6 +15,7 @@ import com.willfp.eco.core.gui.GUIFactory
 import com.willfp.eco.core.integrations.placeholder.PlaceholderIntegration
 import com.willfp.eco.core.proxy.Cleaner
 import com.willfp.eco.core.proxy.ProxyFactory
+import com.willfp.eco.core.requirement.RequirementFactory
 import com.willfp.eco.core.scheduling.Scheduler
 import com.willfp.eco.internal.EcoCleaner
 import com.willfp.eco.internal.Plugins
@@ -30,6 +31,7 @@ import com.willfp.eco.internal.gui.EcoGUIFactory
 import com.willfp.eco.internal.integrations.PlaceholderIntegrationPAPI
 import com.willfp.eco.internal.logging.EcoLogger
 import com.willfp.eco.internal.proxy.EcoProxyFactory
+import com.willfp.eco.internal.requirement.EcoRequirementFactory
 import com.willfp.eco.internal.scheduling.EcoScheduler
 import com.willfp.eco.proxy.FastItemStackFactoryProxy
 import com.willfp.eco.spigot.integrations.bstats.MetricHandler
@@ -39,6 +41,7 @@ import java.util.logging.Logger
 @Suppress("UNUSED")
 class EcoHandler : EcoSpigotPlugin(), Handler {
     private val cleaner = EcoCleaner()
+    private val requirementFactory = EcoRequirementFactory()
 
     override fun createScheduler(plugin: EcoPlugin): Scheduler {
         return EcoScheduler(plugin)
@@ -119,4 +122,8 @@ class EcoHandler : EcoSpigotPlugin(), Handler {
     override fun registerBStats(plugin: EcoPlugin) {
         MetricHandler.createMetrics(plugin, this.ecoPlugin)
     }
+
+    override fun getRequirementFactory(): RequirementFactory {
+        return requirementFactory
+    }
 }

eco-core/core-plugin/src/main/kotlin/com/willfp/eco/spigot/EcoSpigotPlugin.kt

@@ -9,6 +9,10 @@ import com.willfp.eco.core.integrations.antigrief.AntigriefManager
 import com.willfp.eco.core.integrations.customitems.CustomItemsManager
 import com.willfp.eco.core.integrations.mcmmo.McmmoManager
 import com.willfp.eco.core.integrations.shop.ShopManager
+import com.willfp.eco.core.items.Items
+import com.willfp.eco.core.items.args.EnchantmentArgParser
+import com.willfp.eco.core.items.args.TextureArgParser
+import com.willfp.eco.internal.display.EcoDisplayHandler
 import com.willfp.eco.internal.drops.DropManager
 import com.willfp.eco.proxy.BlockBreakProxy
 import com.willfp.eco.proxy.FastItemStackFactoryProxy
@@ -20,6 +24,7 @@ import com.willfp.eco.spigot.eventlisteners.*
 import com.willfp.eco.spigot.gui.GUIListener
 import com.willfp.eco.spigot.integrations.anticheat.*
 import com.willfp.eco.spigot.integrations.antigrief.*
+import com.willfp.eco.spigot.integrations.customitems.CustomItemsItemsAdder
 import com.willfp.eco.spigot.integrations.customitems.CustomItemsOraxen
 import com.willfp.eco.spigot.integrations.mcmmo.McmmoIntegrationImpl
 import com.willfp.eco.spigot.integrations.shop.ShopShopGuiPlus
@@ -41,13 +46,23 @@ abstract class EcoSpigotPlugin : EcoPlugin(
     "&a"
 ) {
     init {
-        Display.setFinalizeKey(namespacedKeyFactory.create("finalized"))
+        Items.registerArgParser(EnchantmentArgParser())
+        Items.registerArgParser(TextureArgParser())
 
         val skullProxy = getProxy(SkullProxy::class.java)
-        SkullUtils.initialize { meta: SkullMeta, base64: String -> skullProxy.setSkullTexture(meta, base64) }
+        SkullUtils.initialize(
+            { meta: SkullMeta, base64: String -> skullProxy.setSkullTexture(meta, base64) },
+            { meta: SkullMeta -> skullProxy.getSkullTexture(meta) }
+        )
 
         val blockBreakProxy = getProxy(BlockBreakProxy::class.java)
         BlockUtils.initialize { player: Player, block: Block -> blockBreakProxy.breakBlock(player, block) }
+
+        postInit()
+    }
+
+    private fun postInit() {
+        Display.handler = EcoDisplayHandler(this)
     }
 
     override fun handleEnable() {
@@ -79,6 +94,7 @@ abstract class EcoSpigotPlugin : EcoPlugin(
 
     override fun handleAfterLoad() {
         CustomItemsManager.registerAllItems()
+        ShopManager.registerEcoProvider()
     }
 
     override fun loadIntegrationLoaders(): List<IntegrationLoader> {
@@ -111,9 +127,10 @@ abstract class EcoSpigotPlugin : EcoPlugin(
 
             // Custom Items
             IntegrationLoader("Oraxen") { CustomItemsManager.register(CustomItemsOraxen()) },
+            IntegrationLoader("ItemsAdder") { CustomItemsManager.register(CustomItemsItemsAdder(this)) },
 
             // Shop
-            IntegrationLoader("ShopGuiPlus") { ShopManager.register(ShopShopGuiPlus()) },
+            IntegrationLoader("ShopGUIPlus") { ShopManager.register(ShopShopGuiPlus()) },
 
             // Misc
             IntegrationLoader("mcMMO") { McmmoManager.register(McmmoIntegrationImpl()) }

eco-core/core-plugin/src/main/kotlin/com/willfp/eco/spigot/gui/GUIListener.kt

@@ -73,9 +73,7 @@ class GUIListener(private val plugin: EcoPlugin) : Listener {
 
         val menu = MenuHandler.getMenu(inv) ?: return
 
-        val rowColumn = MenuUtils.convertSlotToRowColumn(inv.firstEmpty())
-        val row = rowColumn.first!!
-        val column = rowColumn.second!!
+        val (row, column) = MenuUtils.convertSlotToRowColumn(inv.firstEmpty())
         val slot = menu.getSlot(row, column)
 
         if (!slot.isCaptive) {

eco-core/core-plugin/src/main/kotlin/com/willfp/eco/spigot/integrations/customitems/CustomItemsItemsAdder.kt

@@ -0,0 +1,36 @@
+package com.willfp.eco.spigot.integrations.customitems
+
+import com.willfp.eco.core.EcoPlugin
+import com.willfp.eco.core.integrations.customitems.CustomItemsWrapper
+import com.willfp.eco.core.items.CustomItem
+import com.willfp.eco.util.NamespacedKeyUtils
+import dev.lone.itemsadder.api.CustomStack
+import dev.lone.itemsadder.api.ItemsAdder
+import org.bukkit.inventory.ItemStack
+import java.util.function.Predicate
+
+class CustomItemsItemsAdder(
+    private val plugin: EcoPlugin
+) : CustomItemsWrapper {
+    override fun registerAllItems() {
+        plugin.scheduler.runLater({
+            for (item in ItemsAdder.getAllItems()) {
+                val stack = item.itemStack
+                val id = item.id
+                val key = NamespacedKeyUtils.create("itemsadder", id.lowercase())
+                CustomItem(
+                    key,
+                    Predicate { test: ItemStack ->
+                        val customStack = CustomStack.byItemStack(test) ?: return@Predicate false
+                        customStack.id.equals(id, ignoreCase = true)
+                    },
+                    stack
+                ).register()
+            }
+        }, 2)
+    }
+
+    override fun getPluginName(): String {
+        return "ItemsAdder"
+    }
+}

eco-core/core-plugin/src/main/kotlin/com/willfp/eco/spigot/integrations/customitems/CustomItemsOraxen.kt

@@ -6,13 +6,15 @@ import com.willfp.eco.util.NamespacedKeyUtils
 import io.th0rgal.oraxen.items.OraxenItems
 import org.bukkit.NamespacedKey
 import org.bukkit.inventory.ItemStack
+import java.util.*
 import java.util.function.Predicate
 
 class CustomItemsOraxen : CustomItemsWrapper {
     override fun registerAllItems() {
         for (item in OraxenItems.getItems()) {
             val stack = item.build()
-            val id: String = OraxenItems.getIdByItem(item)
+            val id: String = Objects.requireNonNullElse(OraxenItems.getIdByItem(item), "")
+            if (id.isEmpty()) continue
             val key: NamespacedKey = NamespacedKeyUtils.create("oraxen", id.lowercase())
             CustomItem(
                 key, Predicate { test: ItemStack ->
@@ -23,4 +25,8 @@ class CustomItemsOraxen : CustomItemsWrapper {
             ).register()
         }
     }
+
+    override fun getPluginName(): String {
+        return "Oraxen"
+    }
 }

eco-core/core-plugin/src/main/kotlin/com/willfp/eco/spigot/integrations/shop/ShopShopGuiPlus.kt

@@ -28,4 +28,8 @@ class ShopShopGuiPlus : ShopWrapper {
             return Items.getCustomItem(itemStack1)?.key == Items.getCustomItem(itemStack2)?.key
         }
     }
+
+    override fun getPluginName(): String {
+        return "ShopGUIPlus"
+    }
 }

eco-core/core-plugin/src/main/resources/plugin.yml

@@ -4,6 +4,7 @@ main: com.willfp.eco.spigot.EcoHandler
 api-version: 1.16
 authors: [Auxilor]
 website: willfp.com
+load: STARTUP
 depend:
   - ProtocolLib
 softdepend:
@@ -20,7 +21,10 @@ softdepend:
   - PlaceholderAPI
   - mcMMO
   - CombatLogX
-  - ShopGuiPlus
+  - ShopGUIPlus
+  - ItemsAdder
+  - Oraxen
+  - HeadDatabase
 libraries:
   - org.reflections:reflections:0.9.12
   - org.apache.maven:maven-artifact:3.0.3

eco-core/core-proxy/src/main/kotlin/com/willfp/eco/proxy/SkullProxy.kt

@@ -8,4 +8,8 @@ interface SkullProxy : AbstractProxy {
         meta: SkullMeta,
         base64: String
     )
+
+    fun getSkullTexture(
+        meta: SkullMeta
+    ): String?
 }

gradle.properties

@@ -1,2 +1,2 @@
-version = 6.6.1
+version = 6.8.0
 plugin-name = eco