Try fixing window items packet on 1.17.1 and 1.18

src/main/java/io/github/retrooper/packetevents/packetwrappers/play/out/windowitems/WrappedPacketOutWindowItems.java

@@ -23,7 +23,6 @@ import io.github.retrooper.packetevents.packetwrappers.NMSPacket;
 import io.github.retrooper.packetevents.packetwrappers.WrappedPacket;
 import io.github.retrooper.packetevents.packetwrappers.api.SendableWrapper;
 import io.github.retrooper.packetevents.utils.nms.NMSUtils;
-import io.github.retrooper.packetevents.utils.reflection.Reflection;
 import io.github.retrooper.packetevents.utils.server.ServerVersion;
 import org.bukkit.inventory.ItemStack;
 
@@ -31,6 +30,8 @@ import java.lang.reflect.Constructor;
 import java.lang.reflect.InvocationTargetException;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Optional;
+
 //TODO Test wrapper
 public class WrappedPacketOutWindowItems extends WrappedPacket implements SendableWrapper {
     private static boolean v_1_17, v_1_17_1;
@@ -38,15 +39,19 @@ public class WrappedPacketOutWindowItems extends WrappedPacket implements Sendab
     private static Class<?> nonNullListClass;
     private static Constructor<?> packetConstructor;
     private int windowID;
+    private int stateID;
     private List<ItemStack> slotData;
+    private ItemStack heldItem;
 
     public WrappedPacketOutWindowItems(NMSPacket packet) {
         super(packet);
     }
 
-    public WrappedPacketOutWindowItems(int windowID, List<ItemStack> slots) {
+    public WrappedPacketOutWindowItems(int windowID, int stateID, List<ItemStack> slots, ItemStack heldItem) {
         this.windowID = windowID;
+        this.stateID = stateID;
         this.slotData = slots;
+        this.heldItem = heldItem;
     }
 
     @Override
@@ -60,15 +65,14 @@ public class WrappedPacketOutWindowItems extends WrappedPacket implements Sendab
                     Constructor<?> nonNullListConstructor = nonNullListClass.getDeclaredConstructors()[0];
                     nonNullListConstructor.setAccessible(true);
                     nonNullListInstance = nonNullListConstructor.newInstance(new ArrayList<>(), null);
-                }
-                else {
+                    packetConstructor = PacketTypeClasses.Play.Server.WINDOW_ITEMS.getConstructor(int.class, int.class, nonNullListClass, NMSUtils.nmsItemStackClass);
+                } else {
                     Constructor<?> nonNullListConstructor = nonNullListClass.getDeclaredConstructor();
                     nonNullListConstructor.setAccessible(true);
                     nonNullListInstance = nonNullListConstructor.newInstance();
+                    packetConstructor = PacketTypeClasses.Play.Server.WINDOW_ITEMS.getConstructor(int.class, nonNullListClass);
                 }
-                packetConstructor = PacketTypeClasses.Play.Server.WINDOW_ITEMS.getConstructor(int.class, nonNullListClass);
-            }
-            else {
+            } else {
                 packetConstructor = PacketTypeClasses.Play.Server.WINDOW_ITEMS.getConstructor();
             }
         } catch (NoSuchMethodException | IllegalAccessException | InvocationTargetException | InstantiationException e) {
@@ -92,6 +96,22 @@ public class WrappedPacketOutWindowItems extends WrappedPacket implements Sendab
         }
     }
 
+    public int getStateId() {
+        if (packet != null) {
+            return readInt(1);
+        } else {
+            return stateID;
+        }
+    }
+
+    public void setStateId(int stateID) {
+        if (packet != null) {
+            writeInt(1, stateID);
+        } else {
+            this.stateID = stateID;
+        }
+    }
+
     public List<ItemStack> getSlots() {
         if (packet != null) {
             List<ItemStack> slots = new ArrayList<>();
@@ -107,8 +127,7 @@ public class WrappedPacketOutWindowItems extends WrappedPacket implements Sendab
                 }
             }
             return slots;
-        }
-        else {
+        } else {
             return slotData;
         }
     }
@@ -128,21 +147,50 @@ public class WrappedPacketOutWindowItems extends WrappedPacket implements Sendab
                 }
                 writeAnyObject(1, nmsItemStacks);
             }
-        }
-        else {
+        } else {
             this.slotData = slots;
         }
     }
 
+    public Optional<ItemStack> getHeldItem() {
+        if (!v_1_17_1) return Optional.empty();
+
+        if (packet != null) {
+            return Optional.ofNullable(NMSUtils.toBukkitItemStack(readObject(0, NMSUtils.nmsItemStackClass)));
+        } else {
+            return Optional.of(heldItem);
+        }
+    }
+
+    public void setHeldItem(ItemStack heldItem) {
+        if (packet != null) {
+            writeObject(0, NMSUtils.toNMSItemStack(heldItem));
+        } else {
+            this.heldItem = heldItem;
+        }
+    }
+
+    private Object getNMSItemHeld() {
+        if (packet != null) {
+            return readObject(0, NMSUtils.nmsItemStackClass);
+        } else {
+            return NMSUtils.toNMSItemStack(heldItem);
+        }
+    }
+
     @Override
     public Object asNMSPacket() throws Exception {
         Object packetInstance;
-        if (v_1_17) {
+
+        if (v_1_17_1) {
+            packetInstance = packetConstructor.newInstance(getWindowId(), stateID, nonNullListInstance, getNMSItemHeld());
+            WrappedPacketOutWindowItems wrappedPacketOutWindowItems = new WrappedPacketOutWindowItems(new NMSPacket(packetInstance));
+            wrappedPacketOutWindowItems.setSlots(getSlots());
+        } else if (v_1_17) {
             packetInstance = packetConstructor.newInstance(getWindowId(), nonNullListInstance);
             WrappedPacketOutWindowItems wrappedPacketOutWindowItems = new WrappedPacketOutWindowItems(new NMSPacket(packetInstance));
             wrappedPacketOutWindowItems.setSlots(getSlots());
-        }
-        else {
+        } else {
             packetInstance = packetConstructor.newInstance();
             WrappedPacketOutWindowItems wrappedPacketOutWindowItems = new WrappedPacketOutWindowItems(new NMSPacket(packetInstance));
             wrappedPacketOutWindowItems.setWindowId(getWindowId());