Add Inventory#close (#5610)

Spigot-API-Patches/0298-Inventory-close.patch

@@ -0,0 +1,26 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Jake Potrebic <jake.m.potrebic@gmail.com>
+Date: Tue, 11 May 2021 14:54:20 -0700
+Subject: [PATCH] Inventory#close
+
+
+diff --git a/src/main/java/org/bukkit/inventory/Inventory.java b/src/main/java/org/bukkit/inventory/Inventory.java
+index 7956aebcb390379677dccf7c9561866cf94c024c..8f00cb2e3bc9963e9657c1b2493e8b015a6664d0 100644
+--- a/src/main/java/org/bukkit/inventory/Inventory.java
++++ b/src/main/java/org/bukkit/inventory/Inventory.java
+@@ -353,6 +353,15 @@ public interface Inventory extends Iterable<ItemStack> {
+      */
+     public void clear();
+ 
++    // Paper start
++    /**
++     * Closes the inventory for all viewers.
++     *
++     * @return the number if viewers the inventory was closed for
++     */
++    public int close();
++    // Paper end
++
+     /**
+      * Gets a list of players viewing the inventory. Note that a player is
+      * considered to be viewing their own inventory and internal crafting