Program: 41958
Project: 41958
Buggy source:
public boolean execute(ICommandSender sender,String[] args) throws Exception {
  if (args.length > 4) {
    throw new BadUsageException(getUsage());
  }
  IPlayer player=(IPlayer)sender;
  if (player.hasPermission(PermissionNames.USER_BIOME)) {
    IWorld world=player.getWorld();
    PlotMapInfo pmi=manager.getMap(world);
    if (manager.isPlotWorld(world)) {
      Plot plot=manager.getPlot(player);
      if (plot != null) {
        Optional<String> biome=Optional.absent();
        if (args.length == 2) {
          biome=serverBridge.getBiome(args[1]);
        }
 else         if (args.length == 3) {
          biome=serverBridge.getBiome(args[1] + "String_Node_Str" + args[2]);
        }
 else         if (args.length == 4) {
          biome=serverBridge.getBiome(args[1] + "String_Node_Str" + args[2]+ "String_Node_Str"+ args[3]);
        }
        if (!biome.isPresent()) {
          player.sendMessage(biome.get() + "String_Node_Str" + C("String_Node_Str"));
          return true;
        }
        String playerName=player.getName();
        if (player.getUniqueId().equals(plot.getOwnerId()) || player.hasPermission("String_Node_Str")) {
          double price=0.0;
          PlotBiomeChangeEvent event=new PlotBiomeChangeEvent(world,plot,player,biome.get());
          plugin.getEventBus().post(event);
          if (manager.isEconomyEnabled(pmi)) {
            price=pmi.getBiomeChangePrice();
            if (serverBridge.has(player,price)) {
              player.sendMessage("String_Node_Str" + serverBridge.getEconomy().get().format(price) + "String_Node_Str");
              return true;
            }
 else             if (!event.isCancelled()) {
              EconomyResponse er=serverBridge.withdrawPlayer(player,price);
              if (!er.transactionSuccess()) {
                player.sendMessage(er.errorMessage);
                serverBridge.getLogger().warning(er.errorMessage);
                return true;
              }
            }
 else {
              return true;
            }
          }
          if (!event.isCancelled()) {
            plot.setBiome(biome.get());
            manager.setBiome(plot);
            plugin.getSqlManager().savePlot(plot);
            player.sendMessage(C("String_Node_Str") + "String_Node_Str" + biome.get()+ "String_Node_Str"+ serverBridge.getEconomy().get().format(price));
            if (isAdvancedLogging()) {
              if (price == 0) {
                serverBridge.getLogger().info(playerName + "String_Node_Str" + C("String_Node_Str")+ "String_Node_Str"+ plot.getId()+ "String_Node_Str"+ C("String_Node_Str")+ "String_Node_Str"+ biome.get());
              }
 else {
                serverBridge.getLogger().info(playerName + "String_Node_Str" + C("String_Node_Str")+ "String_Node_Str"+ plot.getId()+ "String_Node_Str"+ C("String_Node_Str")+ "String_Node_Str"+ biome.get()+ ("String_Node_Str" + C("String_Node_Str") + "String_Node_Str"+ price));
              }
            }
          }
        }
 else {
          player.sendMessage(C("String_Node_Str") + "String_Node_Str" + plot.getId()+ "String_Node_Str"+ C("String_Node_Str"));
        }
      }
 else {
        player.sendMessage(C("String_Node_Str") + C("String_Node_Str"));
      }
    }
 else {
      player.sendMessage(C("String_Node_Str"));
      return true;
    }
  }
 else {
    return false;
  }
  return true;
}

Fixed version (ground truth):
public boolean execute(ICommandSender sender,String[] args) throws Exception {
  if (args.length > 4) {
    throw new BadUsageException(getUsage());
  }
  IPlayer player=(IPlayer)sender;
  if (player.hasPermission(PermissionNames.USER_BIOME)) {
    IWorld world=player.getWorld();
    PlotMapInfo pmi=manager.getMap(world);
    if (manager.isPlotWorld(world)) {
      Plot plot=manager.getPlot(player);
      if (plot != null) {
        Optional<String> biome=Optional.absent();
        if (args.length == 2) {
          biome=serverBridge.getBiome(args[1]);
        }
 else         if (args.length == 3) {
          biome=serverBridge.getBiome(args[1] + "String_Node_Str" + args[2]);
        }
 else         if (args.length == 4) {
          biome=serverBridge.getBiome(args[1] + "String_Node_Str" + args[2]+ "String_Node_Str"+ args[3]);
        }
        if (!biome.isPresent()) {
          player.sendMessage(biome.get() + "String_Node_Str" + C("String_Node_Str"));
          return true;
        }
        String playerName=player.getName();
        if (player.getUniqueId().equals(plot.getOwnerId()) || player.hasPermission("String_Node_Str")) {
          double price=0.0;
          PlotBiomeChangeEvent event=new PlotBiomeChangeEvent(world,plot,player,biome.get());
          plugin.getEventBus().post(event);
          if (manager.isEconomyEnabled(pmi)) {
            price=pmi.getBiomeChangePrice();
            if (serverBridge.has(player,price)) {
              player.sendMessage("String_Node_Str" + serverBridge.getEconomy().get().format(price) + "String_Node_Str");
              return true;
            }
 else             if (!event.isCancelled()) {
              EconomyResponse er=serverBridge.withdrawPlayer(player,price);
              if (!er.transactionSuccess()) {
                player.sendMessage(er.errorMessage);
                serverBridge.getLogger().warning(er.errorMessage);
                return true;
              }
            }
 else {
              return true;
            }
          }
          if (!event.isCancelled()) {
            plot.setBiome(biome.get());
            manager.setBiome(plot);
            plugin.getSqlManager().savePlot(plot);
            player.sendMessage(C("String_Node_Str") + "String_Node_Str" + biome.get());
            if (isAdvancedLogging()) {
              if (price == 0) {
                serverBridge.getLogger().info(playerName + "String_Node_Str" + C("String_Node_Str")+ "String_Node_Str"+ plot.getId()+ "String_Node_Str"+ C("String_Node_Str")+ "String_Node_Str"+ biome.get());
              }
 else {
                serverBridge.getLogger().info(playerName + "String_Node_Str" + C("String_Node_Str")+ "String_Node_Str"+ plot.getId()+ "String_Node_Str"+ C("String_Node_Str")+ "String_Node_Str"+ biome.get()+ ("String_Node_Str" + C("String_Node_Str") + "String_Node_Str"+ price));
              }
            }
          }
        }
 else {
          player.sendMessage(C("String_Node_Str") + "String_Node_Str" + plot.getId()+ "String_Node_Str"+ C("String_Node_Str"));
        }
      }
 else {
        player.sendMessage(C("String_Node_Str") + C("String_Node_Str"));
      }
    }
 else {
      player.sendMessage(C("String_Node_Str"));
      return true;
    }
  }
 else {
    return false;
  }
  return true;
}