Program: 12905
Project: 12905
Buggy source:
@Override public void doAction(Side to){
  if (this.getNetmask() == 8) {
    UpdaterPassStationEvent event=new UpdaterPassStationEvent(this,this.getSignAddress());
    Bukkit.getServer().getPluginManager().callEvent(event);
  }
  if (this.getStart().empty() ^ this.getEnd().empty())   return;
  int start;
  if (to.Value() != Side.RIGHT.Value() && this.getNetmask() < 8) {
    if (this.isExactSubnet((start=this.getCurrentSubnet()),this.getNetmask())) {
      if (!this.getSignAddress().isValid()) {
        this.getSignAddress().setAddress(buildAddress(start));
        this.getSignAddress().finalizeAddress();
        this.getContent().updateTimestamp();
      }
      this.leaveSubnet();
      this.save();
    }
    return;
  }
  int length=(256 >> this.getNetmask());
  if (!getSignAddress().isValid() || this.needUpdate()) {
    Address old=this.getSignAddress();
    if ((start=this.getFreeSubnet(getNetmask())) != -1) {
      String address=buildAddress(start);
      this.getSignAddress().setAddress(address);
      this.getSignAddress().finalizeAddress();
      Address reloadAddress=AddressFactory.getAddress(address);
      this.setSignAddress(reloadAddress);
      this.getContent().updateTimestamp();
      if (length > 1) {
        UpdaterSetSubnetEvent event=new UpdaterSetSubnetEvent(this,old,reloadAddress,length);
        Bukkit.getServer().getPluginManager().callEvent(event);
      }
 else {
        UpdaterSetStationEvent event=new UpdaterSetStationEvent(this,old,reloadAddress);
        Bukkit.getServer().getPluginManager().callEvent(event);
      }
      if (ByteCart.debug)       ByteCart.log.info("String_Node_Str" + address + "String_Node_Str"+ this.getSignAddress().toString()+ "String_Node_Str");
    }
  }
  int stationfield=-1;
  if (getSignAddress().isValid())   stationfield=this.getSignAddress().getStation().getAmount();
  if (length != 1) {
    if (!this.isInSubnet(stationfield,this.getNetmask()))     leaveSubnet();
    if (stationfield != -1) {
      Stack<Integer> startstack=this.getStart();
      Stack<Integer> endstack=this.getEnd();
      Integer oldstart=startstack.peek();
      Integer oldend=endstack.peek();
      startstack.push(stationfield);
      endstack.push(stationfield + length);
      UpdaterEnterSubnetEvent event=new UpdaterEnterSubnetEvent(this,getSignAddress(),length,AddressFactory.getAddress(buildAddress(oldstart)),oldend - oldstart);
      Bukkit.getServer().getPluginManager().callEvent(event);
    }
  }
 else   if (stationfield != -1)   this.getCounter().incrementCount(stationfield,64);
  save();
}

Fixed version (ground truth):
@Override public void doAction(Side to){
  if (this.getNetmask() == 8) {
    UpdaterPassStationEvent event=new UpdaterPassStationEvent(this,this.getSignAddress());
    Bukkit.getServer().getPluginManager().callEvent(event);
  }
  if (this.getStart().empty() ^ this.getEnd().empty())   return;
  int start;
  if (to.Value() != Side.RIGHT.Value() && this.getNetmask() < 8) {
    if (this.isExactSubnet((start=this.getFirstStationNumber()),this.getNetmask())) {
      if (!this.getSignAddress().isValid()) {
        this.getSignAddress().setAddress(buildAddress(start));
        this.getSignAddress().finalizeAddress();
        this.getContent().updateTimestamp();
      }
      this.leaveSubnet();
      this.save();
    }
    return;
  }
  int length=(256 >> this.getNetmask());
  if (!getSignAddress().isValid() || this.needUpdate()) {
    Address old=this.getSignAddress();
    if ((start=this.getFreeSubnet(getNetmask())) != -1) {
      String address=buildAddress(start);
      this.getSignAddress().setAddress(address);
      this.getSignAddress().finalizeAddress();
      Address reloadAddress=AddressFactory.getAddress(address);
      this.setSignAddress(reloadAddress);
      this.getContent().updateTimestamp();
      if (length > 1) {
        UpdaterSetSubnetEvent event=new UpdaterSetSubnetEvent(this,old,reloadAddress,length);
        Bukkit.getServer().getPluginManager().callEvent(event);
      }
 else {
        UpdaterSetStationEvent event=new UpdaterSetStationEvent(this,old,reloadAddress);
        Bukkit.getServer().getPluginManager().callEvent(event);
      }
      if (ByteCart.debug)       ByteCart.log.info("String_Node_Str" + address + "String_Node_Str"+ this.getSignAddress().toString()+ "String_Node_Str");
    }
  }
  int stationfield=-1;
  if (getSignAddress().isValid())   stationfield=this.getSignAddress().getStation().getAmount();
  if (length != 1) {
    if (!this.isInSubnet(stationfield,this.getNetmask()))     leaveSubnet();
    if (stationfield != -1) {
      Stack<Integer> startstack=this.getStart();
      Stack<Integer> endstack=this.getEnd();
      int oldstart=getFirstStationNumber();
      int oldend=getLastStationNumber();
      startstack.push(stationfield);
      endstack.push(stationfield + length);
      UpdaterEnterSubnetEvent event=new UpdaterEnterSubnetEvent(this,getSignAddress(),length,AddressFactory.getAddress(buildAddress(oldstart)),oldend - oldstart);
      Bukkit.getServer().getPluginManager().callEvent(event);
    }
  }
 else   if (stationfield != -1)   this.getCounter().incrementCount(stationfield,64);
  save();
}