diff --git a/paper-api/src/main/java/org/bukkit/inventory/Inventory.java b/paper-api/src/main/java/org/bukkit/inventory/Inventory.java
index e4bc9afd59..043da1cf82 100644
--- a/paper-api/src/main/java/org/bukkit/inventory/Inventory.java
+++ b/paper-api/src/main/java/org/bukkit/inventory/Inventory.java
@@ -104,7 +104,7 @@ public interface Inventory {
      * @param materialId The materialId to look for
      * @return The Slots found.
      */
-    public HashMap<Integer,ItemStack> all(int materialId); 
+    public HashMap<Integer, ? extends ItemStack> all(int materialId); 
 
     /**
      * Find all slots in the inventory containing any ItemStacks with the given material
@@ -112,7 +112,7 @@ public interface Inventory {
      * @param materialId The material to look for
      * @return The Slots found.
      */
-    public HashMap<Integer,ItemStack> all(Material material); 
+    public HashMap<Integer, ? extends ItemStack> all(Material material); 
 
     /**
      * Find all slots in the inventory containing any ItemStacks with the given ItemStack
@@ -121,7 +121,7 @@ public interface Inventory {
      * @param item The ItemStack to match against
      * @return The Slots found.
      */
-    public HashMap<Integer,ItemStack> all(ItemStack item);
+    public HashMap<Integer, ? extends ItemStack> all(ItemStack item);
 
     /**
      * Find the first slot in the inventory containing an ItemStack with the given materialId
diff --git a/paper-api/src/main/java/org/bukkit/inventory/ItemStack.java b/paper-api/src/main/java/org/bukkit/inventory/ItemStack.java
index 3d6df5d38e..f7b509bc6d 100644
--- a/paper-api/src/main/java/org/bukkit/inventory/ItemStack.java
+++ b/paper-api/src/main/java/org/bukkit/inventory/ItemStack.java
@@ -30,21 +30,21 @@ public class ItemStack {
     }
 
     public ItemStack(final int type, final int amount, final byte damage) {
-        this(type, amount, damage, (byte) 0);
+        this(type, amount, damage, null);
     }
 
     public ItemStack(final Material type, final int amount, final byte damage) {
         this(type.getId(), amount, damage);
     }
 
-    public ItemStack(final int type, final int amount, final byte damage, final byte data) {
+    public ItemStack(final int type, final int amount, final byte damage, final Byte data) {
         this.type = type;
         this.amount = amount;
         this.damage = damage;
-        createData(data);
+        if (data != null) createData(data);
     }
 
-    public ItemStack(final Material type, final int amount, final byte damage, final byte data) {
+    public ItemStack(final Material type, final int amount, final byte damage, final Byte data) {
         this(type.getId(), amount, damage, data);
     }
 
diff --git a/paper-api/src/main/java/org/bukkit/inventory/PlayerInventory.java b/paper-api/src/main/java/org/bukkit/inventory/PlayerInventory.java
index 983fec4b0e..0e82ca0e15 100644
--- a/paper-api/src/main/java/org/bukkit/inventory/PlayerInventory.java
+++ b/paper-api/src/main/java/org/bukkit/inventory/PlayerInventory.java
@@ -74,7 +74,7 @@ public interface PlayerInventory extends Inventory {
     /**
      * Returns the ItemStack currently hold
      * 
-     * @return The currently holded ItemStack
+     * @return The currently held ItemStack
      */
     public ItemStack getItemInHand();