SPIGOT-2272: Add API for virtual Merchants

By: Lukas Hennig <lukas@wirsindwir.de>

paper-api/src/main/java/org/bukkit/entity/Villager.java

@@ -1,14 +1,13 @@
 package org.bukkit.entity;
 
-import java.util.List;
 import org.bukkit.inventory.Inventory;
 import org.bukkit.inventory.InventoryHolder;
-import org.bukkit.inventory.MerchantRecipe;
+import org.bukkit.inventory.Merchant;
 
 /**
  * Represents a villager NPC
  */
-public interface Villager extends Ageable, NPC, InventoryHolder {
+public interface Villager extends Ageable, NPC, InventoryHolder, Merchant {
 
     /**
      * Gets the current profession of this villager.
@@ -24,48 +23,6 @@ public interface Villager extends Ageable, NPC, InventoryHolder {
      */
     public void setProfession(Profession profession);
 
-    /**
-     * Get a list of trades currently available from this villager.
-     *
-     * @return an immutable list of trades
-     */
-    List<MerchantRecipe> getRecipes();
-
-    /**
-     * Set the list of trades currently available from this villager.
-     * <br>
-     * This will not change the selected trades of players currently trading
-     * with this villager.
-     *
-     * @param recipes a list of recipes
-     */
-    void setRecipes(List<MerchantRecipe> recipes);
-
-    /**
-     * Get the recipe at a certain index of this villager's trade list.
-     *
-     * @param i the index
-     * @return the recipe
-     * @throws IndexOutOfBoundsException
-     */
-    MerchantRecipe getRecipe(int i) throws IndexOutOfBoundsException;
-
-    /**
-     * Set the recipe at a certain index of this villager's trade list.
-     *
-     * @param i the index
-     * @param recipe the recipe
-     * @throws IndexOutOfBoundsException
-     */
-    void setRecipe(int i, MerchantRecipe recipe) throws IndexOutOfBoundsException;
-
-    /**
-     * Get the number of trades this villager currently has available.
-     *
-     * @return the recipe count
-     */
-    int getRecipeCount();
-
     /**
      * Gets this villager's inventory.
      * <br>
@@ -77,21 +34,6 @@ public interface Villager extends Ageable, NPC, InventoryHolder {
     @Override
     Inventory getInventory();
 
-    /**
-     * Gets whether this villager is currently trading.
-     *
-     * @return whether the villager is trading
-     */
-    boolean isTrading();
-
-    /**
-     * Gets the player this villager is trading with, or null if it is not
-     * currently trading.
-     *
-     * @return the trader, or null
-     */
-    HumanEntity getTrader();
-
     /**
      * Gets this villager's riches, the number of emeralds this villager has
      * been given.