Program: 44343
Project: 44343
Buggy source:
public void onPlayerCommandPreprocess(PlayerCommandPreprocessEvent event){
  String[] split=event.getMessage().split("String_Node_Str");
  Player player=event.getPlayer();
  if (split[0].equals("String_Node_Str") || split[0].equals("String_Node_Str")) {
    if (split.length == 2 || split.length == 3) {
      String parameter1=split[1];
      if (Util.isNumeric(parameter1)) {
        int counter=0;
        int page=Integer.parseInt(parameter1);
        int x1;
        if (page == 1) {
          x1=1;
        }
 else {
          x1=10 * page;
        }
        int x2=x1 + 8;
        player.sendMessage(Variables.plugin_prefix + "String_Node_Str" + page+ "String_Node_Str");
        for (        Language l : Language.values()) {
          if (counter >= x1 && counter <= x2) {
            player.sendMessage(Variables.plugin_prefix + Util.Capitalize(l.name().toLowerCase()) + "String_Node_Str"+ l);
          }
          counter++;
        }
      }
 else       if (parameter1.equals("String_Node_Str") || parameter1.equals("String_Node_Str")) {
        if (split.length == 3) {
          int counter=0;
          String parameter2=split[2];
          player.sendMessage(Variables.plugin_prefix + "String_Node_Str" + parameter2+ "String_Node_Str");
          for (          Language l : Language.values()) {
            if (!l.name().toLowerCase().equals("String_Node_Str")) {
              if (l.name().toLowerCase().startsWith(parameter2.toLowerCase())) {
                player.sendMessage(TempPrefix + Util.Capitalize(l.name().toLowerCase()) + "String_Node_Str"+ l);
                counter++;
              }
 else               if (l.toString().toLowerCase().startsWith(parameter2.toLowerCase())) {
                player.sendMessage(TempPrefix + Util.Capitalize(l.name().toLowerCase()) + "String_Node_Str"+ l);
                counter++;
              }
            }
          }
          if (counter == 0) {
            player.sendMessage(TempPrefix + "String_Node_Str" + parameter2+ "String_Node_Str");
          }
        }
 else {
          player.sendMessage(Variables.plugin_prefix + "String_Node_Str");
        }
      }
 else       if (translation.IsLanguageSupported(parameter1)) {
        if (!Util.ToFile("String_Node_Str",event.getPlayer().getName().toLowerCase(),null)) {
          Util.ToFile("String_Node_Str",event.getPlayer().getName().toLowerCase() + "String_Node_Str" + parameter1,null);
          String CountryCode=translation.GetCountryCode(playerManager.getIP(event.getPlayer()));
          if (CountryCode.equals("String_Node_Str")) {
            CountryCode="String_Node_Str";
          }
          Util.PlayerDatabase("String_Node_Str",event.getPlayer(),parameter1,CountryCode);
        }
 else {
          String CountryCode=translation.GetCountryCode(playerManager.getIP(event.getPlayer()));
          if (CountryCode.equals("String_Node_Str")) {
            CountryCode="String_Node_Str";
          }
          Util.PlayerDatabase("String_Node_Str",event.getPlayer(),parameter1,CountryCode);
          Util.ToFile("String_Node_Str",event.getPlayer().getName().toLowerCase(),parameter1);
          player.sendMessage(Variables.plugin_prefix + "String_Node_Str");
          player.sendMessage(TempPrefix + "String_Node_Str" + translation.LanguageName(parameter1)+ "String_Node_Str");
        }
      }
 else {
        player.sendMessage(Variables.plugin_prefix + "String_Node_Str");
        player.sendMessage(TempPrefix + "String_Node_Str");
        player.sendMessage(TempPrefix + "String_Node_Str");
      }
    }
 else {
      boolean isin=Util.PlayerDatabase("String_Node_Str",event.getPlayer(),null,null);
      Language lang;
      if (isin) {
        lang=translation.GetPlayerLanguageHash(event.getPlayer());
      }
 else {
        lang=translation.GetLanguage(event.getPlayer(),"String_Node_Str");
      }
      player.sendMessage(Variables.plugin_prefix + "String_Node_Str" + translation.LanguageName("String_Node_Str" + lang)+ "String_Node_Str");
      player.sendMessage(TempPrefix + "String_Node_Str");
      player.sendMessage(TempPrefix + "String_Node_Str");
      player.sendMessage(TempPrefix + "String_Node_Str");
    }
    event.setCancelled(true);
  }
}

Fixed version (ground truth):
public void onPlayerCommandPreprocess(PlayerCommandPreprocessEvent event){
  String[] split=event.getMessage().split("String_Node_Str");
  Player player=event.getPlayer();
  if (split[0].equals("String_Node_Str") || split[0].equals("String_Node_Str")) {
    if (split.length == 2 || split.length == 3) {
      String parameter1=split[1];
      if (util.isNumeric(parameter1)) {
        int counter=0;
        int page=Integer.parseInt(parameter1);
        int x1;
        if (page == 1) {
          x1=1;
        }
 else {
          x1=10 * page;
        }
        int x2=x1 + 8;
        player.sendMessage(Variables.plugin_prefix + "String_Node_Str" + page+ "String_Node_Str");
        for (        Language l : Language.values()) {
          if (counter >= x1 && counter <= x2) {
            player.sendMessage(Variables.plugin_prefix + util.capitalize(l.name().toLowerCase()) + "String_Node_Str"+ l);
          }
          counter++;
        }
      }
 else       if (parameter1.equals("String_Node_Str") || parameter1.equals("String_Node_Str")) {
        if (split.length == 3) {
          int counter=0;
          String parameter2=split[2];
          player.sendMessage(Variables.plugin_prefix + "String_Node_Str" + parameter2+ "String_Node_Str");
          for (          Language l : Language.values()) {
            if (!l.name().toLowerCase().equals("String_Node_Str")) {
              if (l.name().toLowerCase().startsWith(parameter2.toLowerCase())) {
                player.sendMessage(TempPrefix + util.capitalize(l.name().toLowerCase()) + "String_Node_Str"+ l);
                counter++;
              }
 else               if (l.toString().toLowerCase().startsWith(parameter2.toLowerCase())) {
                player.sendMessage(TempPrefix + util.capitalize(l.name().toLowerCase()) + "String_Node_Str"+ l);
                counter++;
              }
            }
          }
          if (counter == 0) {
            player.sendMessage(TempPrefix + "String_Node_Str" + parameter2+ "String_Node_Str");
          }
        }
 else {
          player.sendMessage(Variables.plugin_prefix + "String_Node_Str");
        }
      }
 else       if (translation.isLanguageSupported(parameter1)) {
        EBean eBeanClass=playerManager.checkPlayer(event.getPlayer(),true);
        eBeanClass.setLanguage(translation.languageName(parameter1));
        eBeanClass.save(eBeanClass);
        player.sendMessage(Variables.plugin_prefix + "String_Node_Str");
        player.sendMessage(TempPrefix + "String_Node_Str" + translation.languageName(parameter1)+ "String_Node_Str");
      }
    }
 else {
      player.sendMessage(Variables.plugin_prefix + "String_Node_Str");
      player.sendMessage(TempPrefix + "String_Node_Str");
      player.sendMessage(TempPrefix + "String_Node_Str");
    }
  }
 else {
    String lang=playerManager.getLanguageString(event.getPlayer());
    player.sendMessage(Variables.plugin_prefix + "String_Node_Str" + lang+ "String_Node_Str");
    player.sendMessage(TempPrefix + "String_Node_Str");
    player.sendMessage(TempPrefix + "String_Node_Str");
    player.sendMessage(TempPrefix + "String_Node_Str");
  }
  event.setCancelled(true);
}