Fix discrepancies in NBT and ItemMeta. Fixes BUKKIT-3279

An ItemStack gains the tag name "tag" when the stack is serialized
to NBT, however items don't have a tag *until* they are serialized at
least once. So to solve this, we remove the tag name when loading the
NBT data.

Another problem with NBT are TagLists, when transferring tag lists
between the server and the client the names are lost, and so we
simply don't add a name to the tag.

By: feildmaster <admin@feildmaster.com>

paper-server/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaBook.java

@@ -91,11 +91,7 @@ class CraftMetaBook extends CraftMetaItem implements BookMeta {
         }
 
         if (hasPages()) {
-            NBTTagList itemPages = new NBTTagList(BOOK_PAGES.NBT);
-            for (int i = 1; i < pages.size() + 1; i++) {
-                itemPages.add(new NBTTagString(String.valueOf(i), pages.get(i - 1)));
-            }
-            itemData.set(BOOK_PAGES.NBT, itemPages);
+            itemData.set(BOOK_PAGES.NBT, createStringList(pages, BOOK_PAGES));
         }
     }
 

paper-server/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaItem.java

@@ -307,11 +307,7 @@ class CraftMetaItem implements ItemMeta, Repairable {
         }
 
         if (hasLore()) {
-            NBTTagList list = new NBTTagList(LORE.NBT);
-            for (int i = 0; i < lore.size(); i++) {
-                list.add(new NBTTagString(String.valueOf(i), lore.get(i)));
-            }
-            setDisplayTag(itemTag, LORE.NBT, list);
+            setDisplayTag(itemTag, LORE.NBT, createStringList(lore, LORE));
         }
 
         applyEnchantments(enchantments, itemTag, ENCHANTMENTS);
@@ -321,6 +317,19 @@ class CraftMetaItem implements ItemMeta, Repairable {
         }
     }
 
+    static NBTTagList createStringList(List<String> list, ItemMetaKey key) {
+        if (list == null || list.isEmpty()) {
+            return null;
+        }
+
+        NBTTagList tagList = new NBTTagList(key.NBT);
+        for (int i = 0; i < list.size(); i++) {
+            tagList.add(new NBTTagString("", list.get(i)));
+        }
+
+        return tagList;
+    }
+
     static void applyEnchantments(Map<Enchantment, Integer> enchantments, NBTTagCompound tag, ItemMetaKey key) {
         if (enchantments == null || enchantments.size() == 0) {
             return;