Fix PlayerEditBookEvent (#5463)

Spigot-API-Patches/0284-Allow-PlayerEditBookEvent-to-fire-for-off-hand.patch

@@ -0,0 +1,19 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: jmp <jasonpenilla2@me.com>
+Date: Mon, 5 Apr 2021 18:35:37 -0700
+Subject: [PATCH] Allow PlayerEditBookEvent to fire for off hand
+
+
+diff --git a/src/main/java/org/bukkit/event/player/PlayerEditBookEvent.java b/src/main/java/org/bukkit/event/player/PlayerEditBookEvent.java
+index c8fda418bd5e0e6c299900be469862dbc5d7a56f..b8994a6d023c124f2c068d2e69f2c3d949b9405e 100644
+--- a/src/main/java/org/bukkit/event/player/PlayerEditBookEvent.java
++++ b/src/main/java/org/bukkit/event/player/PlayerEditBookEvent.java
+@@ -24,7 +24,7 @@ public class PlayerEditBookEvent extends PlayerEvent implements Cancellable {
+     public PlayerEditBookEvent(@NotNull Player who, int slot, @NotNull BookMeta previousBookMeta, @NotNull BookMeta newBookMeta, boolean isSigning) {
+         super(who);
+ 
+-        Validate.isTrue(slot >= -1 && slot <= 8, "Slot must be in range (-1)-8 inclusive");
++        Validate.isTrue(slot == 40 || slot >= -1 && slot <= 8, "Slot must be in range (-1)-8 inclusive"); // Paper - off hand is 40
+         Validate.notNull(previousBookMeta, "Previous book meta must not be null");
+         Validate.notNull(newBookMeta, "New book meta must not be null");
+ 

Spigot-Server-Patches/0700-Don-t-ignore-result-of-PlayerEditBookEvent.patch

@@ -0,0 +1,19 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: jmp <jasonpenilla2@me.com>
+Date: Mon, 5 Apr 2021 18:35:15 -0700
+Subject: [PATCH] Don't ignore result of PlayerEditBookEvent
+
+
+diff --git a/src/main/java/net/minecraft/server/network/PlayerConnection.java b/src/main/java/net/minecraft/server/network/PlayerConnection.java
+index 5ee56f3636b299280a7c2bc5a210c63250a47fb3..e6ea84ba098b4d77bc68e99862992a10ef4585b5 100644
+--- a/src/main/java/net/minecraft/server/network/PlayerConnection.java
++++ b/src/main/java/net/minecraft/server/network/PlayerConnection.java
+@@ -1144,7 +1144,7 @@ public class PlayerConnection implements PacketListenerPlayIn {
+             list.stream().map(NBTTagString::a).forEach(nbttaglist::add);
+             ItemStack old = itemstack.cloneItemStack(); // CraftBukkit
+             itemstack.a("pages", (NBTBase) nbttaglist);
+-            CraftEventFactory.handleEditBookEvent(player, i, old, itemstack); // CraftBukkit
++            this.player.inventory.setItem(i, CraftEventFactory.handleEditBookEvent(player, i, old, itemstack)); // CraftBukkit // Paper - Don't ignore result (see other callsite for handleEditBookEvent)
+         }
+     }
+