Program: 80908
Project: 80908
Buggy source:
public List<IPlayer> getPlayers(Collection<String> filter,ProxiedPlayer who,boolean includeSuspectors){
  List<IPlayer> list=new ArrayList<>();
  Iterable<IPlayer> players=Iterables.concat(Collections2.transform(playerProviders,new Function<IPlayerProvider,Iterable<? extends IPlayer>>(){
    @Override public Iterable<? extends IPlayer> apply(    IPlayerProvider iPlayerProvider){
      return iPlayerProvider.getPlayers();
    }
  }
));
  for (  IPlayer p : players) {
    boolean areGroupRules=false;
    boolean areServerRules=false;
    boolean fitGroupRules=false;
    boolean fitServerRules=false;
    String group=plugin.getPermissionManager().getMainGroup(p);
    for (    String rule : filter) {
      if (rule.isEmpty()) {
      }
 else {
        Optional<ServerInfo> server=p.getServer();
        if (rule.equalsIgnoreCase("String_Node_Str")) {
          areServerRules=true;
          if (server.isPresent() && who.getServer() != null) {
            if (server.get().getName().equalsIgnoreCase(who.getServer().getInfo().getName())) {
              fitServerRules=true;
            }
          }
        }
 else         if (isServer(rule)) {
          areServerRules=true;
          if (server.isPresent()) {
            if (server.get().getName().equalsIgnoreCase(rule)) {
              fitServerRules=true;
            }
            String[] s=rule.split("String_Node_Str");
            if (s.length == 2) {
              if (server.get().getName().equalsIgnoreCase(s[0])) {
                Optional<String> world=plugin.getBridge().getPlayerInformation(p,Values.Player.Bukkit.World);
                if (world.isPresent()) {
                  if (world.get().equalsIgnoreCase(s[1])) {
                    fitServerRules=true;
                  }
                }
              }
            }
          }
        }
 else {
          areGroupRules=true;
          if (group != null) {
            if (group.equalsIgnoreCase(rule)) {
              fitGroupRules=true;
            }
          }
        }
      }
    }
    if (((!areServerRules) || fitServerRules) && ((!areGroupRules) || fitGroupRules) && !BungeeTabListPlus.isHidden(p,who)&& (includeSuspectors || p.getGameMode() != 3)) {
      list.add(p);
    }
  }
  return list;
}

Fixed version (ground truth):
public List<IPlayer> getPlayers(Collection<String> filter,ProxiedPlayer who,boolean includeSuspectors){
  List<IPlayer> list=new ArrayList<>();
  for (  IPlayer p : players) {
    boolean areGroupRules=false;
    boolean areServerRules=false;
    boolean fitGroupRules=false;
    boolean fitServerRules=false;
    String group=plugin.getPermissionManager().getMainGroup(p);
    for (    String rule : filter) {
      if (rule.isEmpty()) {
      }
 else {
        Optional<ServerInfo> server=p.getServer();
        if (rule.equalsIgnoreCase("String_Node_Str")) {
          areServerRules=true;
          if (server.isPresent() && who.getServer() != null) {
            if (server.get().getName().equalsIgnoreCase(who.getServer().getInfo().getName())) {
              fitServerRules=true;
            }
          }
        }
 else         if (plugin.isServer(rule)) {
          areServerRules=true;
          if (server.isPresent()) {
            if (server.get().getName().equalsIgnoreCase(rule)) {
              fitServerRules=true;
            }
            String[] s=rule.split("String_Node_Str");
            if (s.length == 2) {
              if (server.get().getName().equalsIgnoreCase(s[0])) {
                Optional<String> world=plugin.getBridge().getPlayerInformation(p,Values.Player.Bukkit.World);
                if (world.isPresent()) {
                  if (world.get().equalsIgnoreCase(s[1])) {
                    fitServerRules=true;
                  }
                }
              }
            }
          }
        }
 else {
          areGroupRules=true;
          if (group != null) {
            if (group.equalsIgnoreCase(rule)) {
              fitGroupRules=true;
            }
          }
        }
      }
    }
    if (((!areServerRules) || fitServerRules) && ((!areGroupRules) || fitGroupRules) && !BungeeTabListPlus.isHidden(p,who)&& (includeSuspectors || p.getGameMode() != 3)) {
      list.add(p);
    }
  }
  return list;
}