Program: 93981
Project: 93981
Buggy source:
public void onEntityDamage(EntityDamageEvent event){
  if (event.getEntity() instanceof Player) {
    Player p=(Player)event.getEntity();
    if (this.plugin.AuthDB_AuthTime.containsKey(p.getName())) {
      long timestamp=System.currentTimeMillis() / 1000;
      long difference=timestamp - this.plugin.AuthDB_AuthTime.get(p.getName());
      if (difference < 5) {
        Util.logging.Debug("String_Node_Str" + difference + "String_Node_Str");
        event.setCancelled(true);
      }
    }
    if (event instanceof EntityDamageByEntityEvent) {
      EntityDamageByEntityEvent e=(EntityDamageByEntityEvent)event;
      if ((e.getDamager() instanceof Animals) || (e.getDamager() instanceof Monster)) {
        if (event.getEntity() instanceof Player && !checkGuest(p,Config.guests_health)) {
          event.setCancelled(true);
        }
      }
 else       if (e.getDamager() instanceof Player && e.getEntity() instanceof Player) {
        Player t=(Player)e.getDamager();
        if (!checkGuest(t,Config.guests_pvp) && !checkGuest(p,Config.guests_health)) {
          event.setCancelled(true);
        }
      }
 else {
        if (!checkGuest(p,Config.guests_health)) {
          event.setCancelled(true);
        }
 else         if (this.plugin.isRegistered("String_Node_Str",p.getName()) == true && plugin.isAuthorized(p) == false) {
          event.setCancelled(true);
        }
      }
    }
 else {
      if (this.plugin.isRegistered("String_Node_Str",p.getName()) == true && plugin.isAuthorized(p) == false) {
        event.setCancelled(true);
        return;
      }
    }
  }
 else   if ((event.getEntity() instanceof Animals) || (event.getEntity() instanceof Monster)) {
    if (!(event instanceof EntityDamageByEntityEvent)) {
      return;
    }
    EntityDamageByEntityEvent e=(EntityDamageByEntityEvent)event;
    if ((e.getDamager() instanceof Player)) {
      Player t=(Player)e.getDamager();
      if (!checkGuest(t,Config.guests_mobdamage)) {
        event.setCancelled(true);
      }
    }
  }
}

Fixed version (ground truth):
public void onEntityDamage(EntityDamageEvent event){
  if (event.getEntity() instanceof Player) {
    Player p=(Player)event.getEntity();
    if (this.plugin.AuthDB_AuthTime.containsKey(p.getName())) {
      long timestamp=System.currentTimeMillis() / 1000;
      long difference=timestamp - this.plugin.AuthDB_AuthTime.get(p.getName());
      if (difference < 5) {
        Util.logging.Debug("String_Node_Str" + difference + "String_Node_Str");
        event.setCancelled(true);
      }
    }
    if (event instanceof EntityDamageByEntityEvent) {
      EntityDamageByEntityEvent e=(EntityDamageByEntityEvent)event;
      if ((e.getDamager() instanceof Animals) || (e.getDamager() instanceof Monster)) {
        if (event.getEntity() instanceof Player && !checkGuest(p,Config.guests_health)) {
          event.setCancelled(true);
        }
      }
 else       if (e.getDamager() instanceof Player && e.getEntity() instanceof Player) {
        Player t=(Player)e.getDamager();
        Util.logging.Debug("String_Node_Str");
        if ((this.plugin.isRegistered("String_Node_Str",p.getName()) == true && plugin.isAuthorized(p) == false) || (!checkGuest(t,Config.guests_pvp) && !checkGuest(p,Config.guests_health))) {
          Util.logging.Debug("String_Node_Str");
          event.setCancelled(true);
        }
      }
 else {
        if (!checkGuest(p,Config.guests_health)) {
          event.setCancelled(true);
        }
 else         if (this.plugin.isRegistered("String_Node_Str",p.getName()) == true && plugin.isAuthorized(p) == false) {
          event.setCancelled(true);
        }
      }
    }
 else {
      if (this.plugin.isRegistered("String_Node_Str",p.getName()) == true && plugin.isAuthorized(p) == false) {
        event.setCancelled(true);
        return;
      }
    }
  }
 else   if ((event.getEntity() instanceof Animals) || (event.getEntity() instanceof Monster)) {
    if (!(event instanceof EntityDamageByEntityEvent)) {
      return;
    }
    EntityDamageByEntityEvent e=(EntityDamageByEntityEvent)event;
    if ((e.getDamager() instanceof Player)) {
      Player t=(Player)e.getDamager();
      if (!checkGuest(t,Config.guests_mobdamage)) {
        event.setCancelled(true);
      }
    }
  }
}