Program: 51596
Project: 51596
Buggy source:
public StockItem getItem(ItemStack itemStack,TraderStatus status,boolean dura,boolean amount){
  boolean equal=false;
  for (  StockItem item : stock.get(status.toString())) {
    equal=false;
    if (itemStack.getType().equals(item.getItemStack().getType())) {
      equal=true;
      if (dura)       equal=itemStack.getDurability() <= item.getItemStack().getDurability();
 else       equal=itemStack.getData().equals(item.getItemStack().getData());
      if (amount && equal)       equal=itemStack.getAmount() >= item.getItemStack().getAmount();
      if (equal) {
        boolean checkEnchant=item.isCheckingEnchantments();
        boolean checkLevel=item.isCheckingEnchantmentLevels();
        if (checkEnchant || checkLevel) {
          Map<Enchantment,Integer> itemStackEnchantments=null;
          Map<Enchantment,Integer> stockItemEnchantments=null;
          if (itemStack.getType().equals(Material.ENCHANTED_BOOK)) {
            EnchantmentStorageMeta itemStackStorageMeta=(EnchantmentStorageMeta)itemStack.getItemMeta();
            if (itemStackStorageMeta != null) {
              itemStackEnchantments=itemStackStorageMeta.getStoredEnchants();
            }
            EnchantmentStorageMeta stockItemStorageMeta=(EnchantmentStorageMeta)item.getItemStack().getItemMeta();
            if (stockItemStorageMeta != null) {
              itemStackEnchantments=stockItemStorageMeta.getStoredEnchants();
            }
          }
 else {
            itemStackEnchantments=itemStack.getEnchantments();
            stockItemEnchantments=item.getItemStack().getEnchantments();
          }
          if (itemStackEnchantments == null || itemStackEnchantments.isEmpty()) {
            equal=(stockItemEnchantments == null || stockItemEnchantments.isEmpty());
          }
 else {
            equal=(stockItemEnchantments != null && !stockItemEnchantments.isEmpty() && itemStackEnchantments.keySet().equals(stockItemEnchantments.keySet()));
          }
          if (equal && checkLevel) {
            for (            Map.Entry<Enchantment,Integer> ench : itemStackEnchantments.entrySet()) {
              if (ench.getValue() != stockItemEnchantments.get(ench.getKey())) {
                equal=false;
                break;
              }
            }
          }
        }
      }
      if (equal)       return item;
    }
  }
  return null;
}

Fixed version (ground truth):
public StockItem getItem(ItemStack itemStack,TraderStatus status,boolean dura,boolean amount){
  boolean equal=false;
  for (  StockItem item : stock.get(status.toString())) {
    equal=false;
    if (itemStack.getType().equals(item.getItemStack().getType())) {
      equal=true;
      if (dura)       equal=itemStack.getDurability() <= item.getItemStack().getDurability();
 else       equal=itemStack.getData().equals(item.getItemStack().getData());
      if (amount && equal)       equal=itemStack.getAmount() >= item.getItemStack().getAmount();
      if (equal) {
        boolean checkEnchant=item.isCheckingEnchantments();
        boolean checkLevel=item.isCheckingEnchantmentLevels();
        if (checkEnchant || checkLevel) {
          Map<Enchantment,Integer> itemStackEnchantments=null;
          Map<Enchantment,Integer> stockItemEnchantments=null;
          if (itemStack.getType().equals(Material.ENCHANTED_BOOK)) {
            EnchantmentStorageMeta itemStackStorageMeta=(EnchantmentStorageMeta)itemStack.getItemMeta();
            if (itemStackStorageMeta != null) {
              itemStackEnchantments=itemStackStorageMeta.getStoredEnchants();
            }
            EnchantmentStorageMeta stockItemStorageMeta=(EnchantmentStorageMeta)item.getItemStack().getItemMeta();
            if (stockItemStorageMeta != null) {
              stockItemEnchantments=stockItemStorageMeta.getStoredEnchants();
            }
          }
 else {
            itemStackEnchantments=itemStack.getEnchantments();
            stockItemEnchantments=item.getItemStack().getEnchantments();
          }
          if (itemStackEnchantments == null || itemStackEnchantments.isEmpty()) {
            equal=(stockItemEnchantments == null || stockItemEnchantments.isEmpty());
          }
 else {
            equal=(stockItemEnchantments != null && !stockItemEnchantments.isEmpty() && itemStackEnchantments.keySet().equals(stockItemEnchantments.keySet()));
          }
          if (equal && checkLevel) {
            for (            Map.Entry<Enchantment,Integer> ench : itemStackEnchantments.entrySet()) {
              if (ench.getValue() != stockItemEnchantments.get(ench.getKey())) {
                equal=false;
                break;
              }
            }
          }
        }
      }
      if (equal)       return item;
    }
  }
  return null;
}