Program: 51680
Project: 51680
Buggy source:
@EventHandler public void inventoryClick(InventoryClickEvent event){
  if (event.getRawSlot() < 0)   return;
  if (event.getWhoClicked() instanceof Player) {
    Player p=(Player)event.getWhoClicked();
    if (state.containsKey(p.getName())) {
      TraderStatus trader=state.get(p.getName());
      InventoryTrait sr=trader.getTrader().getTrait(InventoryTrait.class);
      boolean top=event.getView().convertSlot(event.getRawSlot()) == event.getRawSlot();
      DecimalFormat f=new DecimalFormat("String_Node_Str");
      if ((!trader.getStatus().equals(Status.PLAYER_MANAGE_SELL) && !trader.getStatus().equals(Status.PLAYER_MANAGE_BUY) && !trader.getStatus().equals(Status.PLAYER_MANAGE_SELL_AMOUT)) && !trader.getStatus().equals(Status.PLAYER_MANAGE_PRICE)) {
        StockItem si=null;
        if (((CitizensTrader)sr.getPlugin()).config.getMode().equals("String_Node_Str") && top) {
          secureMode(event,trader,si,sr);
          return;
        }
 else         if (((CitizensTrader)sr.getPlugin()).config.getMode().equals("String_Node_Str"))         simpleMode(event,trader,si,sr);
        event.setCancelled(true);
      }
 else {
        if ((event.getCurrentItem().equals(new ItemStack(Material.WOOL,1,(short)0,(byte)3)) && (event.getSlot() == trader.getInventory().getSize() - 1)) || (event.getCurrentItem().equals(new ItemStack(Material.WOOL,1,(short)0,(byte)5)) && (event.getSlot() == trader.getInventory().getSize() - 1)) || (event.getCurrentItem().equals(new ItemStack(Material.WOOL,1,(short)0,(byte)15)) && (event.getSlot() == trader.getInventory().getSize() - 2))|| (event.getCurrentItem().equals(new ItemStack(Material.WOOL,1,(short)0,(byte)14)) && (event.getSlot() == trader.getInventory().getSize() - 2))|| (event.getCurrentItem().equals(new ItemStack(Material.WOOL,1)) && (event.getSlot() == trader.getInventory().getSize() - 2)))         event.setCancelled(true);
        StockItem si=null;
        if (top) {
          if (event.isShiftClick()) {
            if (trader.getStatus().equals(Status.PLAYER_MANAGE_SELL)) {
              si=sr.itemForSell(event.getSlot());
              if (si != null) {
                trader.getInventory().clear();
                InventoryTrait.setInventoryWith(trader.getInventory(),si);
                trader.setStatus(Status.PLAYER_MANAGE_SELL_AMOUT);
                trader.setStockItem(si);
              }
            }
            event.setCancelled(true);
          }
 else {
            if (event.getCurrentItem().equals(new ItemStack(Material.WOOL,1)) && (event.getSlot() == trader.getInventory().getSize() - 2)) {
              trader.setStatus(Status.PLAYER_MANAGE_PRICE);
              trader.getInventory().setItem(trader.getInventory().getSize() - 2,new ItemStack(Material.WOOL,1,(short)0,(byte)15));
              return;
            }
 else             if (trader.getStatus().equals(Status.PLAYER_MANAGE_SELL)) {
              if (event.isRightClick()) {
                p.sendMessage(ChatColor.GOLD + "String_Node_Str");
                event.setCancelled(true);
                return;
              }
              if (trader.getStockItem() == null) {
                trader.setStockItem(sr.itemForSell(event.getSlot()));
                if (trader.getStockItem() == null)                 if (event.getCurrentItem().equals(new ItemStack(Material.WOOL,1,(short)0,(byte)5)) && (event.getSlot() == trader.getInventory().getSize() - 1)) {
                  trader.getInventory().clear();
                  sr.inventoryView(trader.getInventory(),Status.PLAYER_MANAGE_BUY);
                  trader.setStatus(Status.PLAYER_MANAGE_BUY);
                  trader.setStockItem(null);
                }
              }
 else {
                StockItem item=trader.getStockItem();
                if (item.getSlot() < 0) {
                  item.getAmouts().clear();
                  item.addAmout(event.getCursor().getAmount());
                  sr.addItem(true,item);
                }
                if (!event.getCurrentItem().getType().equals(Material.AIR))                 trader.setStockItem(sr.itemForSell(event.getSlot()));
 else                 trader.setStockItem(null);
                item.setSlot(event.getSlot());
              }
            }
 else             if (trader.getStatus().equals(Status.PLAYER_MANAGE_SELL_AMOUT)) {
              if (!event.getCursor().getType().equals(Material.AIR) && !(event.getCursor().getType().equals(trader.getStockItem().getItemStack().getType()) && event.getCursor().getData().equals(trader.getStockItem().getItemStack().getData())) || (!event.getCurrentItem().getType().equals(trader.getStockItem().getItemStack().getType()) && !event.getCurrentItem().getType().equals(Material.AIR))) {
                p.sendMessage(ChatColor.GOLD + "String_Node_Str");
                event.setCancelled(true);
              }
              if (event.getCurrentItem().equals(new ItemStack(Material.WOOL,1,(short)0,(byte)14)) && (event.getSlot() == trader.getInventory().getSize() - 1)) {
                sr.saveNewAmouts(trader.getInventory(),trader.getStockItem());
                trader.getInventory().clear();
                sr.inventoryView(trader.getInventory(),Status.PLAYER_MANAGE_SELL);
                trader.setStatus(Status.PLAYER_MANAGE_SELL);
                trader.setStockItem(null);
              }
            }
 else             if (trader.getStatus().equals(Status.PLAYER_MANAGE_BUY)) {
              if (event.isRightClick()) {
                p.sendMessage(ChatColor.GOLD + "String_Node_Str");
                event.setCancelled(true);
                return;
              }
              if (trader.getStockItem() == null) {
                trader.setStockItem(sr.wantItemBuy(event.getSlot()));
                if (trader.getStockItem() == null) {
                  if (event.getCurrentItem().equals(new ItemStack(Material.WOOL,1)) && (event.getSlot() == trader.getInventory().getSize() - 2)) {
                    trader.setStatus(Status.PLAYER_MANAGE_PRICE);
                    trader.getInventory().setItem(trader.getInventory().getSize() - 2,new ItemStack(Material.WOOL,1,(short)0,(byte)15));
                  }
 else                   if (event.getCurrentItem().equals(new ItemStack(Material.WOOL,1,(short)0,(byte)3)) && (event.getSlot() == trader.getInventory().getSize() - 1)) {
                    trader.getInventory().clear();
                    sr.inventoryView(trader.getInventory(),Status.PLAYER_MANAGE_SELL);
                    trader.setStatus(Status.PLAYER_MANAGE_SELL);
                    trader.setStockItem(null);
                  }
                }
              }
 else {
                StockItem item=trader.getStockItem();
                if (item.getSlot() < 0) {
                  item.getAmouts().clear();
                  item.addAmout(event.getCursor().getAmount());
                  sr.addItem(false,item);
                }
                if (!event.getCurrentItem().getType().equals(Material.AIR))                 trader.setStockItem(sr.wantItemBuy(event.getSlot()));
 else                 trader.setStockItem(null);
                item.setSlot(event.getSlot());
              }
            }
 else             if (trader.getStatus().equals(Status.PLAYER_MANAGE_PRICE)) {
              if (trader.getInventory().getItem(trader.getInventory().getSize() - 1).equals(new ItemStack(Material.WOOL,1,(short)0,(byte)5)))               si=sr.itemForSell(event.getSlot());
 else               si=sr.wantItemBuy(event.getSlot());
              if (si != null) {
                if (event.isLeftClick())                 si.increasePrice(this.getManagePriceAmout(event.getCursor()));
 else                 if (event.isRightClick())                 si.lowerPrice(this.getManagePriceAmout(event.getCursor()));
                p.sendMessage(ChatColor.GOLD + "String_Node_Str" + f.format(si.getPrice() / si.getAmouts().get(0)));
                event.setCancelled(true);
              }
 else {
                if (event.getCurrentItem().equals(new ItemStack(Material.WOOL,1,(short)0,(byte)15)) && (event.getSlot() == trader.getInventory().getSize() - 2)) {
                  if (trader.getInventory().getItem(trader.getInventory().getSize() - 1).equals(new ItemStack(Material.WOOL,1,(short)0,(byte)5)))                   trader.setStatus(Status.PLAYER_MANAGE_SELL);
 else                   trader.setStatus(Status.PLAYER_MANAGE_BUY);
                  trader.getInventory().setItem(trader.getInventory().getSize() - 2,new ItemStack(Material.WOOL,1));
                }
 else                 p.sendMessage(ChatColor.GOLD + "String_Node_Str");
              }
            }
          }
          trader.setLastInv(true);
        }
 else {
          if (trader.getStatus().equals(Status.PLAYER_MANAGE_SELL) || trader.getStatus().equals(Status.PLAYER_MANAGE_BUY)) {
            if (trader.getLastInv() && trader.getStockItem() != null) {
              StockItem item=trader.getStockItem();
              if (trader.getStatus().equals(Status.PLAYER_MANAGE_SELL))               if (sr.itemForSell(item.getSlot()).equals(item))               sr.removeItem(true,trader.getStockItem().getSlot());
              if (trader.getStatus().equals(Status.PLAYER_MANAGE_BUY))               if (sr.wantItemBuy(item.getSlot()).equals(item))               sr.removeItem(false,trader.getStockItem().getSlot());
              trader.setStockItem(null);
            }
 else {
              ItemStack is=event.getCurrentItem();
              String itemInfo=is.getTypeId() + "String_Node_Str" + is.getData().getData()+ "String_Node_Str"+ is.getAmount()+ "String_Node_Str"+ is.getDurability();
              if (!is.getEnchantments().isEmpty()) {
                itemInfo+="String_Node_Str";
                for (                Enchantment ench : is.getEnchantments().keySet())                 itemInfo+=ench.getId() + "String_Node_Str" + is.getEnchantmentLevel(ench)+ "String_Node_Str";
              }
              trader.setStockItem(new StockItem(itemInfo));
            }
          }
 else {
          }
          trader.setLastInv(false);
        }
      }
    }
  }
}

Fixed version (ground truth):
@EventHandler public void inventoryClick(InventoryClickEvent event){
  if (event.getRawSlot() < 0)   return;
  if (event.getWhoClicked() instanceof Player) {
    Player p=(Player)event.getWhoClicked();
    if (state.containsKey(p.getName())) {
      TraderStatus trader=state.get(p.getName());
      InventoryTrait sr=trader.getTrader().getTrait(InventoryTrait.class);
      boolean top=event.getView().convertSlot(event.getRawSlot()) == event.getRawSlot();
      DecimalFormat f=new DecimalFormat("String_Node_Str");
      if ((!trader.getStatus().equals(Status.PLAYER_MANAGE_SELL) && !trader.getStatus().equals(Status.PLAYER_MANAGE_BUY) && !trader.getStatus().equals(Status.PLAYER_MANAGE_SELL_AMOUT)) && !trader.getStatus().equals(Status.PLAYER_MANAGE_PRICE)) {
        StockItem si=null;
        if (((CitizensTrader)sr.getPlugin()).config.getMode().equals("String_Node_Str")) {
          secureMode(event,trader,si,sr);
          return;
        }
 else         if (((CitizensTrader)sr.getPlugin()).config.getMode().equals("String_Node_Str"))         simpleMode(event,trader,si,sr);
        event.setCancelled(true);
      }
 else {
        if ((event.getCurrentItem().equals(new ItemStack(Material.WOOL,1,(short)0,(byte)3)) && (event.getSlot() == trader.getInventory().getSize() - 1)) || (event.getCurrentItem().equals(new ItemStack(Material.WOOL,1,(short)0,(byte)5)) && (event.getSlot() == trader.getInventory().getSize() - 1)) || (event.getCurrentItem().equals(new ItemStack(Material.WOOL,1,(short)0,(byte)15)) && (event.getSlot() == trader.getInventory().getSize() - 2))|| (event.getCurrentItem().equals(new ItemStack(Material.WOOL,1,(short)0,(byte)14)) && (event.getSlot() == trader.getInventory().getSize() - 2))|| (event.getCurrentItem().equals(new ItemStack(Material.WOOL,1)) && (event.getSlot() == trader.getInventory().getSize() - 2)))         event.setCancelled(true);
        StockItem si=null;
        if (top) {
          if (event.isShiftClick()) {
            if (trader.getStatus().equals(Status.PLAYER_MANAGE_SELL)) {
              si=sr.itemForSell(event.getSlot());
              if (si != null) {
                trader.getInventory().clear();
                InventoryTrait.setInventoryWith(trader.getInventory(),si);
                trader.setStatus(Status.PLAYER_MANAGE_SELL_AMOUT);
                trader.setStockItem(si);
              }
            }
            event.setCancelled(true);
          }
 else {
            if (event.getCurrentItem().equals(new ItemStack(Material.WOOL,1)) && (event.getSlot() == trader.getInventory().getSize() - 2)) {
              trader.setStatus(Status.PLAYER_MANAGE_PRICE);
              trader.getInventory().setItem(trader.getInventory().getSize() - 2,new ItemStack(Material.WOOL,1,(short)0,(byte)15));
              return;
            }
 else             if (trader.getStatus().equals(Status.PLAYER_MANAGE_SELL)) {
              if (event.isRightClick()) {
                p.sendMessage(ChatColor.GOLD + "String_Node_Str");
                event.setCancelled(true);
                return;
              }
              if (trader.getStockItem() == null) {
                trader.setStockItem(sr.itemForSell(event.getSlot()));
                if (trader.getStockItem() == null)                 if (event.getCurrentItem().equals(new ItemStack(Material.WOOL,1,(short)0,(byte)5)) && (event.getSlot() == trader.getInventory().getSize() - 1)) {
                  trader.getInventory().clear();
                  sr.inventoryView(trader.getInventory(),Status.PLAYER_MANAGE_BUY);
                  trader.setStatus(Status.PLAYER_MANAGE_BUY);
                  trader.setStockItem(null);
                }
              }
 else {
                StockItem item=trader.getStockItem();
                if (item.getSlot() < 0) {
                  item.getAmouts().clear();
                  item.addAmout(event.getCursor().getAmount());
                  sr.addItem(true,item);
                }
                if (!event.getCurrentItem().getType().equals(Material.AIR))                 trader.setStockItem(sr.itemForSell(event.getSlot()));
 else                 trader.setStockItem(null);
                item.setSlot(event.getSlot());
              }
            }
 else             if (trader.getStatus().equals(Status.PLAYER_MANAGE_SELL_AMOUT)) {
              if (!event.getCursor().getType().equals(Material.AIR) && !(event.getCursor().getType().equals(trader.getStockItem().getItemStack().getType()) && event.getCursor().getData().equals(trader.getStockItem().getItemStack().getData())) || (!event.getCurrentItem().getType().equals(trader.getStockItem().getItemStack().getType()) && !event.getCurrentItem().getType().equals(Material.AIR))) {
                p.sendMessage(ChatColor.GOLD + "String_Node_Str");
                event.setCancelled(true);
              }
              if (event.getCurrentItem().equals(new ItemStack(Material.WOOL,1,(short)0,(byte)14)) && (event.getSlot() == trader.getInventory().getSize() - 1)) {
                sr.saveNewAmouts(trader.getInventory(),trader.getStockItem());
                trader.getInventory().clear();
                sr.inventoryView(trader.getInventory(),Status.PLAYER_MANAGE_SELL);
                trader.setStatus(Status.PLAYER_MANAGE_SELL);
                trader.setStockItem(null);
              }
            }
 else             if (trader.getStatus().equals(Status.PLAYER_MANAGE_BUY)) {
              if (event.isRightClick()) {
                p.sendMessage(ChatColor.GOLD + "String_Node_Str");
                event.setCancelled(true);
                return;
              }
              if (trader.getStockItem() == null) {
                trader.setStockItem(sr.wantItemBuy(event.getSlot()));
                if (trader.getStockItem() == null) {
                  if (event.getCurrentItem().equals(new ItemStack(Material.WOOL,1)) && (event.getSlot() == trader.getInventory().getSize() - 2)) {
                    trader.setStatus(Status.PLAYER_MANAGE_PRICE);
                    trader.getInventory().setItem(trader.getInventory().getSize() - 2,new ItemStack(Material.WOOL,1,(short)0,(byte)15));
                  }
 else                   if (event.getCurrentItem().equals(new ItemStack(Material.WOOL,1,(short)0,(byte)3)) && (event.getSlot() == trader.getInventory().getSize() - 1)) {
                    trader.getInventory().clear();
                    sr.inventoryView(trader.getInventory(),Status.PLAYER_MANAGE_SELL);
                    trader.setStatus(Status.PLAYER_MANAGE_SELL);
                    trader.setStockItem(null);
                  }
                }
              }
 else {
                StockItem item=trader.getStockItem();
                if (item.getSlot() < 0) {
                  item.getAmouts().clear();
                  item.addAmout(event.getCursor().getAmount());
                  sr.addItem(false,item);
                }
                if (!event.getCurrentItem().getType().equals(Material.AIR))                 trader.setStockItem(sr.wantItemBuy(event.getSlot()));
 else                 trader.setStockItem(null);
                item.setSlot(event.getSlot());
              }
            }
 else             if (trader.getStatus().equals(Status.PLAYER_MANAGE_PRICE)) {
              if (trader.getInventory().getItem(trader.getInventory().getSize() - 1).equals(new ItemStack(Material.WOOL,1,(short)0,(byte)5)))               si=sr.itemForSell(event.getSlot());
 else               si=sr.wantItemBuy(event.getSlot());
              if (si != null) {
                if (event.isLeftClick())                 si.increasePrice(this.getManagePriceAmout(event.getCursor()));
 else                 if (event.isRightClick())                 si.lowerPrice(this.getManagePriceAmout(event.getCursor()));
                p.sendMessage(ChatColor.GOLD + "String_Node_Str" + f.format(si.getPrice() / si.getAmouts().get(0)));
                event.setCancelled(true);
              }
 else {
                if (event.getCurrentItem().equals(new ItemStack(Material.WOOL,1,(short)0,(byte)15)) && (event.getSlot() == trader.getInventory().getSize() - 2)) {
                  if (trader.getInventory().getItem(trader.getInventory().getSize() - 1).equals(new ItemStack(Material.WOOL,1,(short)0,(byte)5)))                   trader.setStatus(Status.PLAYER_MANAGE_SELL);
 else                   trader.setStatus(Status.PLAYER_MANAGE_BUY);
                  trader.getInventory().setItem(trader.getInventory().getSize() - 2,new ItemStack(Material.WOOL,1));
                }
 else                 p.sendMessage(ChatColor.GOLD + "String_Node_Str");
              }
            }
          }
          trader.setLastInv(true);
        }
 else {
          if (trader.getStatus().equals(Status.PLAYER_MANAGE_SELL) || trader.getStatus().equals(Status.PLAYER_MANAGE_BUY)) {
            if (trader.getLastInv() && trader.getStockItem() != null) {
              StockItem item=trader.getStockItem();
              if (trader.getStatus().equals(Status.PLAYER_MANAGE_SELL))               if (sr.itemForSell(item.getSlot()).equals(item))               sr.removeItem(true,trader.getStockItem().getSlot());
              if (trader.getStatus().equals(Status.PLAYER_MANAGE_BUY))               if (sr.wantItemBuy(item.getSlot()).equals(item))               sr.removeItem(false,trader.getStockItem().getSlot());
              trader.setStockItem(null);
            }
 else {
              ItemStack is=event.getCurrentItem();
              String itemInfo=is.getTypeId() + "String_Node_Str" + is.getData().getData()+ "String_Node_Str"+ is.getAmount()+ "String_Node_Str"+ is.getDurability();
              if (!is.getEnchantments().isEmpty()) {
                itemInfo+="String_Node_Str";
                for (                Enchantment ench : is.getEnchantments().keySet())                 itemInfo+=ench.getId() + "String_Node_Str" + is.getEnchantmentLevel(ench)+ "String_Node_Str";
              }
              trader.setStockItem(new StockItem(itemInfo));
            }
          }
 else {
          }
          trader.setLastInv(false);
        }
      }
    }
  }
}