java - Google Cloud Print sometimes gives false errors -

i have java application uses google cloud print api (https://github.com/jittagornp/googlecloudprint) print pdf's. in cases works charm every , (approx 1 out of 100) gives error looks "det går inte att göra ändringar ett avslutat jobb". translated english reads: "can't make changes finished job" kicker pages prints every time, or without error.

code looks every call gcp:

    public static submitjobresponse submitprintjob(string filename, string type){          string jsonticket;         string printerid;          submitjobresponse response = null;          string jobtitle;          jobtitle = filename.substring(filename.lastindexof('/') + 1);          // login gcp         googlecloudprint cloudprint = gcplogin();          jsonticket = "{'version':'1.0','print':{'vendor_ticket_item':[],'color':{'type':1},'copies':{'copies':4}}}";         printerid = session("printerlabel");           try {              // file byte array             path path = paths.get(filename);             byte[] content = files.readallbytes(path);              gson gson = new gson();             ticket ticket = gson.fromjson(jsonticket, ticket.class);              string json = gson.tojson(ticket);              //create job             submitjob submitjob = new submitjob();             submitjob.setcontent(content);             submitjob.setcontenttype("application/pdf");             submitjob.setprinterid(printerid);             submitjob.setticket(ticket);             submitjob.settitle(jobtitle);              //send job             response = cloudprint.submitjob(submitjob);             logger.debug("printerid => {}", printerid);             logger.debug("submit job response => {}", response.issuccess() + "," + response.getmessage());              if(response.issuccess()) {                 logger.debug("submit job id => {}", response.getjob().getid());             }              cloudprint.disconnect();          } catch (exception ex) {             logger.warn(null, ex);         }          return response;      } 

the api uses call "/submit?output=json&printerid=" @ gcp why i'm trying change finished job - i'm not submitting job id - printer id.

how rid of these false errors?