PaperMC/nms-patches/TileEntityLectern.patch

--- a/net/minecraft/server/TileEntityLectern.java
+++ b/net/minecraft/server/TileEntityLectern.java
@@ -1,10 +1,63 @@
 package net.minecraft.server;
 
 import javax.annotation.Nullable;
+// CraftBukkit start
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import org.bukkit.Location;
+import org.bukkit.block.Lectern;
+import org.bukkit.craftbukkit.block.CraftBlock;
+import org.bukkit.craftbukkit.entity.CraftHumanEntity;
+import org.bukkit.entity.HumanEntity;
+import org.bukkit.inventory.InventoryHolder;
+// CraftBukkit end
 
-public class TileEntityLectern extends TileEntity implements Clearable, ITileInventory {
+public class TileEntityLectern extends TileEntity implements Clearable, ITileInventory, ICommandListener { // CraftBukkit - ICommandListener
+
+    // CraftBukkit start - add fields and methods
+    public final IInventory inventory = new LecternInventory();
+    public class LecternInventory implements IInventory {
+
+        public List<HumanEntity> transaction = new ArrayList<>();
+        private int maxStack = 1;
+
+        @Override
+        public List<ItemStack> getContents() {
+            return Arrays.asList(book);
+        }
+
+        @Override
+        public void onOpen(CraftHumanEntity who) {
+            transaction.add(who);
+        }
+
+        @Override
+        public void onClose(CraftHumanEntity who) {
+            transaction.remove(who);
+        }
+
+        @Override
+        public List<HumanEntity> getViewers() {
+            return transaction;
+        }
+
+        @Override
+        public void setMaxStackSize(int i) {
+            maxStack = i;
+        }
+
+        @Override
+        public Location getLocation() {
+            return new Location(world.getWorld(), position.getX(), position.getY(), position.getZ());
+        }
+
+        @Override
+        public InventoryHolder getOwner() {
+            return (Lectern) TileEntityLectern.this.getOwner();
+        }
+        // CraftBukkit end
 
-    public final IInventory inventory = new IInventory() {
         @Override
         public int getSize() {
             return 1;
@@ -49,11 +102,18 @@
         }
 
         @Override
-        public void setItem(int i, ItemStack itemstack) {}
+        // CraftBukkit start
+        public void setItem(int i, ItemStack itemstack) {
+            if (i == 0) {
+                TileEntityLectern.this.setBook(itemstack);
+                BlockLectern.setHasBook(TileEntityLectern.this.getWorld(), TileEntityLectern.this.getPosition(), TileEntityLectern.this.getBlock(), TileEntityLectern.this.hasBook());
+            }
+        }
+        // CraftBukkit end
 
         @Override
         public int getMaxStackSize() {
-            return 1;
+            return maxStack; // CraftBukkit
         }
 
         @Override
@@ -158,6 +218,32 @@
         return itemstack;
     }
 
+    // CraftBukkit start
+    @Override
+    public void sendMessage(IChatBaseComponent ichatbasecomponent) {
+    }
+
+    @Override
+    public org.bukkit.command.CommandSender getBukkitSender(CommandListenerWrapper wrapper) {
+        return wrapper.getEntity() != null ? wrapper.getEntity().getBukkitSender(wrapper) : new org.bukkit.craftbukkit.command.CraftBlockCommandSender(wrapper, this);
+    }
+
+    @Override
+    public boolean shouldSendSuccess() {
+        return false;
+    }
+
+    @Override
+    public boolean shouldSendFailure() {
+        return false;
+    }
+
+    @Override
+    public boolean shouldBroadcastCommands() {
+        return false;
+    }
+
+    // CraftBukkit end
     private CommandListenerWrapper a(@Nullable EntityHuman entityhuman) {
         String s;
         Object object;
@@ -172,7 +258,8 @@
 
         Vec3D vec3d = new Vec3D((double) this.position.getX() + 0.5D, (double) this.position.getY() + 0.5D, (double) this.position.getZ() + 0.5D);
 
-        return new CommandListenerWrapper(ICommandListener.DUMMY, vec3d, Vec2F.a, (WorldServer) this.world, 2, s, (IChatBaseComponent) object, this.world.getMinecraftServer(), entityhuman);
+        // CraftBukkit - this
+        return new CommandListenerWrapper(this, vec3d, Vec2F.a, (WorldServer) this.world, 2, s, (IChatBaseComponent) object, this.world.getMinecraftServer(), entityhuman);
     }
 
     @Override
@@ -206,7 +293,7 @@
 
     @Override
     public Container createMenu(int i, PlayerInventory playerinventory, EntityHuman entityhuman) {
-        return new ContainerLectern(i, this.inventory, this.containerProperties);
+        return new ContainerLectern(i, this.inventory, this.containerProperties, playerinventory); // CraftBukkit
     }
 
     @Override