Program: 51668
Project: 51668
Buggy source:
public boolean createTrader(Player player,String[] args){
  String traderName="String_Node_Str";
  EntityType entityType=EntityType.PLAYER;
  TraderType traderType=getDefaultTraderType(player);
  WalletType walletType=getDefaultWalletType(player);
  for (  String arg : args) {
    if (arg.startsWith("String_Node_Str")) {
      if (!permsManager.has(player,"String_Node_Str" + arg.substring(2))) {
        player.sendMessage(locale.getLocaleString("String_Node_Str"));
        return true;
      }
      traderType=TraderType.getTypeByName(arg.substring(2));
    }
 else     if (arg.startsWith("String_Node_Str")) {
      if (!permsManager.has(player,"String_Node_Str" + arg.substring(2))) {
        player.sendMessage(locale.getLocaleString("String_Node_Str"));
        return true;
      }
      walletType=WalletType.getTypeByName(arg.substring(2));
    }
 else     if (arg.startsWith("String_Node_Str")) {
      if (!permsManager.has(player,"String_Node_Str" + arg.substring(2))) {
        player.sendMessage(locale.getLocaleString("String_Node_Str"));
        return true;
      }
      entityType=EntityType.fromName(arg.substring(2));
    }
 else {
      traderName+=arg + "String_Node_Str";
    }
  }
  if (traderName.isEmpty())   traderName="String_Node_Str";
 else   traderName=traderName.substring(7,traderName.length() - 1);
  if (walletType == null || traderType == null || entityType == null) {
    player.sendMessage(locale.getLocaleString("String_Node_Str"));
    return true;
  }
  NPC npc=CitizensAPI.getNPCRegistry().createNPC(entityType,traderName);
  npc.addTrait(TraderCharacterTrait.class);
  npc.addTrait(MobType.class);
  npc.getTrait(MobType.class).setType(entityType);
  npc.spawn(player.getLocation());
  TraderTrait settings=npc.getTrait(TraderCharacterTrait.class).getTraderTrait();
  settings.setTraderType(traderType);
  settings.setWalletType(walletType);
  settings.setOwner(player.getName());
  player.sendMessage(locale.getLocaleString("String_Node_Str"));
  return true;
}

Fixed version (ground truth):
public boolean createTrader(Player player,String[] args){
  String traderName="String_Node_Str";
  EntityType entityType=EntityType.PLAYER;
  TraderType traderType=getDefaultTraderType(player);
  WalletType walletType=getDefaultWalletType(player);
  for (  String arg : args) {
    if (arg.startsWith("String_Node_Str")) {
      if (!permsManager.has(player,"String_Node_Str" + arg.substring(2))) {
        player.sendMessage(locale.getLocaleString("String_Node_Str"));
        return true;
      }
      traderType=TraderType.getTypeByName(arg.substring(2));
    }
 else     if (arg.startsWith("String_Node_Str")) {
      if (!permsManager.has(player,"String_Node_Str" + arg.substring(2))) {
        player.sendMessage(locale.getLocaleString("String_Node_Str"));
        return true;
      }
      walletType=WalletType.getTypeByName(arg.substring(2));
    }
 else     if (arg.startsWith("String_Node_Str")) {
      if (!permsManager.has(player,"String_Node_Str" + arg.substring(2))) {
        player.sendMessage(locale.getLocaleString("String_Node_Str"));
        return true;
      }
      entityType=EntityType.fromName(arg.substring(2));
    }
 else {
      traderName+=arg + "String_Node_Str";
    }
  }
  if (traderName.isEmpty())   traderName="String_Node_Str";
 else   traderName=traderName.substring(7,traderName.length() - 1);
  if (walletType == null || traderType == null || entityType == null) {
    player.sendMessage(locale.getLocaleString("String_Node_Str"));
    return true;
  }
  NPC npc=CitizensAPI.getNPCRegistry().createNPC(entityType,traderName);
  npc.addTrait(TraderCharacterTrait.class);
  npc.addTrait(MobType.class);
  npc.getTrait(MobType.class).setType(entityType);
  npc.spawn(player.getLocation());
  TraderTrait settings=npc.getTrait(TraderCharacterTrait.class).getTraderTrait();
  npc.getTrait(TraderCharacterTrait.class).setTraderType(traderType);
  settings.setWalletType(walletType);
  settings.setOwner(player.getName());
  player.sendMessage(locale.getLocaleString("String_Node_Str"));
  return true;
}