gt:         if (this.tag == null) {
context: package net.minecraft.server;
  
  public final class ItemStack {
  
      public int count;
      public int b;
      public int id;
      public NBTTagCompound tag;
      private int damage;
      private EntityItemFrame f;
  
      public ItemStack(Block block) {
          this(block, 1);
      }
  
      public ItemStack(Block block, int i) {
          this(block.id, i, 0);
      }
  
      public ItemStack(Block block, int i, int j) {
          this(block.id, i, j);
      }
  
      public ItemStack(Item item) {
          this(item.id, 1, 0);
      }
  
      public ItemStack(Item item, int i) {
          this(item.id, i, 0);
      }
  
      public ItemStack(Item item, int i, int j) {
          this(item.id, i, j);
      }
  
      public ItemStack(int i, int j, int k) {
          this.count = 0;
          this.f = null;
          this.id = i;
          this.count = j;
          this.setData(k); // CraftBukkit
      }
  
      public static ItemStack createStack(NBTTagCompound nbttagcompound) {
          ItemStack itemstack = new ItemStack();
  
          itemstack.c(nbttagcompound);
          return itemstack.getItem() != null ? itemstack : null;
      }
  
      private ItemStack() {
          this.count = 0;
          this.f = null;
      }
  
      public ItemStack a(int i) {
          ItemStack itemstack = new ItemStack(this.id, i, this.damage);
  
          if (this.tag != null) {
              itemstack.tag = (NBTTagCompound) this.tag.clone();
          }
  
          this.count -= i;
          return itemstack;
      }
  
      public Item getItem() {
          return Item.byId[this.id];
      }
  
      public boolean placeItem(EntityHuman entityhuman, World world, int i, int j, int k, int l, float f, float f1, float f2) {
          boolean flag = this.getItem().interactWith(this, entityhuman, world, i, j, k, l, f, f1, f2);
  
          if (flag) {
              entityhuman.a(StatisticList.E[this.id], 1);
          }
  
          return flag;
      }
  
      public float a(Block block) {
          return this.getItem().getDestroySpeed(this, block);
      }
  
      public ItemStack a(World world, EntityHuman entityhuman) {
          return this.getItem().a(this, world, entityhuman);
      }
  
      public ItemStack b(World world, EntityHuman entityhuman) {
          return this.getItem().b(this, world, entityhuman);
      }
  
      public NBTTagCompound save(NBTTagCompound nbttagcompound) {
          nbttagcompound.setShort("id", (short) this.id);
          nbttagcompound.setByte("Count", (byte) this.count);
          nbttagcompound.setShort("Damage", (short) this.damage);
          if (this.tag != null) {
              nbttagcompound.set("tag", this.tag.clone()); // CraftBukkit - make defensive copy, data is going to another thread
          }
  
          return nbttagcompound;
      }
  
      public void c(NBTTagCompound nbttagcompound) {
          this.id = nbttagcompound.getShort("id");
          this.count = nbttagcompound.getByte("Count");
          this.damage = nbttagcompound.getShort("Damage");
          if (nbttagcompound.hasKey("tag")) {
              // CraftBukkit - clear name from compound and make defensive copy as this data may be coming from the save thread
              this.tag = (NBTTagCompound) nbttagcompound.getCompound("tag").clone().setName("");
          }
      }
  
      public int getMaxStackSize() {
          return this.getItem().getMaxStackSize();
      }
  
      public boolean isStackable() {
          return this.getMaxStackSize() > 1 && (!this.f() || !this.h());
      }
  
      public boolean f() {
          return Item.byId[this.id].getMaxDurability() > 0;
      }
  
      public boolean usesData() {
          return Item.byId[this.id].l();
      }
  
      public boolean h() {
          return this.f() && this.damage > 0;
      }
  
      public int i() {
          return this.damage;
      }
  
      public int getData() {
          return this.damage;
      }
  
      public void setData(int i) {
          this.damage = (this.id > 0) && (this.id < 256) && (this.id != Block.ANVIL.id) ? Item.byId[this.id].filterData(i) : i; // CraftBukkit
      }
  
      public int k() {
          return Item.byId[this.id].getMaxDurability();
      }
  
      public void damage(int i, EntityLiving entityliving) {
          if (this.f()) {
              if (i > 0 && entityliving instanceof EntityHuman) {
                  int j = EnchantmentManager.getEnchantmentLevel(Enchantment.DURABILITY.id, this);
                  int k = 0;
  
                  for (int l = 0; j > 0 && l < i; ++l) {
                      if (EnchantmentDurability.a(this, j, entityliving.world.random)) {
                          ++k;
                      }
                  }
  
                  i -= k;
                  if (i <= 0) {
                      return;
                  }
              }
  
              if (!(entityliving instanceof EntityHuman) || !((EntityHuman) entityliving).abilities.canInstantlyBuild) {
                  this.damage += i;
              }
  
              if (this.damage > this.k()) {
                  entityliving.a(this);
                  if (entityliving instanceof EntityHuman) {
                      ((EntityHuman) entityliving).a(StatisticList.F[this.id], 1);
                  }
  
                  --this.count;
                  if (this.count < 0) {
                      this.count = 0;
                  }
  
                  // CraftBukkit start - Check for item breaking
                  if (this.count == 0 && entityliving instanceof EntityHuman) {
                      org.bukkit.craftbukkit.event.CraftEventFactory.callPlayerItemBreakEvent((EntityHuman) entityliving, this);
                  }
                  // CraftBukkit end
  
                  this.damage = 0;
              }
          }
      }
  
      public void a(EntityLiving entityliving, EntityHuman entityhuman) {
          boolean flag = Item.byId[this.id].a(this, entityliving, (EntityLiving) entityhuman);
  
          if (flag) {
              entityhuman.a(StatisticList.E[this.id], 1);
          }
      }
  
      public void a(World world, int i, int j, int k, int l, EntityHuman entityhuman) {
          boolean flag = Item.byId[this.id].a(this, world, i, j, k, l, entityhuman);
  
          if (flag) {
              entityhuman.a(StatisticList.E[this.id], 1);
          }
      }
  
      public int a(Entity entity) {
          return Item.byId[this.id].a(entity);
      }
  
      public boolean b(Block block) {
          return Item.byId[this.id].canDestroySpecialBlock(block);
      }
  
      public boolean a(EntityLiving entityliving) {
          return Item.byId[this.id].a(this, entityliving);
      }
  
      public ItemStack cloneItemStack() {
          ItemStack itemstack = new ItemStack(this.id, this.count, this.damage);
  
          if (this.tag != null) {
              itemstack.tag = (NBTTagCompound) this.tag.clone();
          }
  
          return itemstack;
      }
  
      public static boolean equals(ItemStack itemstack, ItemStack itemstack1) {
          return itemstack == null && itemstack1 == null ? true : (itemstack != null && itemstack1 != null ? (itemstack.tag == null && itemstack1.tag != null ? false : itemstack.tag == null || itemstack.tag.equals(itemstack1.tag)) : false);
      }
  
      public static boolean matches(ItemStack itemstack, ItemStack itemstack1) {
          return itemstack == null && itemstack1 == null ? true : (itemstack != null && itemstack1 != null ? itemstack.d(itemstack1) : false);
      }
  
      private boolean d(ItemStack itemstack) {
          return this.count != itemstack.count ? false : (this.id != itemstack.id ? false : (this.damage != itemstack.damage ? false : (this.tag == null && itemstack.tag != null ? false : this.tag == null || this.tag.equals(itemstack.tag))));
      }
  
      public boolean doMaterialsMatch(ItemStack itemstack) {
          return this.id == itemstack.id && this.damage == itemstack.damage;
      }
  
      public String a() {
          return Item.byId[this.id].d(this);
      }
  
      public static ItemStack b(ItemStack itemstack) {
          return itemstack == null ? null : itemstack.cloneItemStack();
      }
  
      public String toString() {
          return this.count + "x" + Item.byId[this.id].getName() + "@" + this.damage;
      }
  
      public void a(World world, Entity entity, int i, boolean flag) {
          if (this.b > 0) {
              --this.b;
          }
  
          Item.byId[this.id].a(this, world, entity, i, flag);
      }
  
      public void a(World world, EntityHuman entityhuman, int i) {
          entityhuman.a(StatisticList.D[this.id], i);
          Item.byId[this.id].d(this, world, entityhuman);
      }
  
      public int m() {
          return this.getItem().c_(this);
      }
  
      public EnumAnimation n() {
          return this.getItem().b_(this);
      }
  
      public void b(World world, EntityHuman entityhuman, int i) {
          this.getItem().a(this, world, entityhuman, i);
      }
  
      public boolean hasTag() {
          return this.tag != null;
      }
  
      public NBTTagCompound getTag() {
          return this.tag;
      }
  
      public NBTTagList getEnchantments() {
          return this.tag == null ? null : (NBTTagList) this.tag.get("ench");
      }
  
      public void setTag(NBTTagCompound nbttagcompound) {
          this.tag = nbttagcompound;
      }
  
      public String r() {
          String s = this.getItem().l(this);
  
          if (this.tag != null && this.tag.hasKey("display")) {
              NBTTagCompound nbttagcompound = this.tag.getCompound("display");
  
              if (nbttagcompound.hasKey("Name")) {
                  s = nbttagcompound.getString("Name");
              }
          }
  
          return s;
      }
  
      public void c(String s) {
          if (this.tag == null) {
              this.tag = new NBTTagCompound();
          }
  
          if (!this.tag.hasKey("display")) {
              this.tag.setCompound("display", new NBTTagCompound());
          }
  
          this.tag.getCompound("display").setString("Name", s);
      }
  
      public boolean s() {
          return this.tag == null ? false : (!this.tag.hasKey("display") ? false : this.tag.getCompound("display").hasKey("Name"));
      }
  
      public boolean v() {
          return !this.getItem().d_(this) ? false : !this.hasEnchantments();
      }
  
      public void addEnchantment(Enchantment enchantment, int i) {
  