#vulnerable code 
                                @Override
    public void execute(final JobDetail jobDetail, JobTriggerType triggerType, JobExecutionContext context) {

        final String appName = jobDetail.getApp().getAppName();
        final String jobClass = jobDetail.getJob().getClazz();

        JobInstance instance = null;
        try {

            Logs.info("The job({}/{}) is fired.", appName, jobClass);

            if (triggerType == JobTriggerType.DEFAULT){
                // refresh the job fire time if triggered by scheduler
                asyncExecutor.submit(new RefreshJobFireTimeTask(appName, jobClass, context));
            }

            if (!canRunJobInstance(appName, jobClass)){
                return;
            }

            // job is running
            jobSupport.updateJobStateDirectly(appName, jobClass, JobState.RUNNING);

            // create the job instance and shards
            instance = createInstanceAndShards(jobDetail, triggerType);

            // trigger the clients to pull shards
            jobSupport.triggerJobInstance(appName, jobClass, instance);

            // blocking until all shards to be finished or timeout
            Long timeout = jobDetail.getConfig().getTimeout();
            timeout = timeout == null ? 0L : timeout;
            JobInstanceWaitResp finishResp = jobSupport.waitingJobInstanceFinish(appName, jobClass, timeout, instance.getId());
            if (finishResp.isSuccess()){
                // job instance is finished successfully
                // publish job finish event
                eventDispatcher.publish(new JobFinishedEvent(instance.getJobId(), instance.getId()));
            } else if (finishResp.isTimeout()){
                // job instance is timeout
                eventDispatcher.publish(new JobTimeoutEvent(instance.getJobId(), instance.getId(), buildJobTimeoutDetail(instance)));
            }

            // maybe now the job is paused, stopped, ..., so need to expect the job state
            jobSupport.updateJobStateSafely(appName, jobClass, JobState.WAITING);

            // job has finished
        } catch (JobStateTransferInvalidException e){
            // job state transfer error
            Logs.warn("failed to update job state(instances={}), cause: {}.", instance, e.toString());
        } catch (JobInstanceCreateException e){
            // handle when job instance create failed
            String cause = Throwables.getStackTraceAsString(e);
            Logs.error("failed to create job instance when execute job(jobDetail={}, instance={}), cause: {}",
                    jobDetail, instance, cause);
            handleJobExecuteFailed(jobDetail, instance, appName, jobClass, cause);
        } catch (Exception e){
            // handle other exceptions
            String cause = Throwables.getStackTraceAsString(e);
            Logs.error("failed to execute job(jobDetail={}, instance={}), cause: {}",
                    jobDetail, instance, cause);
            handleJobExecuteFailed(jobDetail, instance, appName, jobClass, cause);
        }
    } 
                            #location 33 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                @Override
    public void execute(final JobDetail jobDetail, JobTriggerType triggerType, JobExecutionContext context) {

        final String appName = jobDetail.getApp().getAppName();
        final String jobClass = jobDetail.getJob().getClazz();

        JobInstance instance = null;
        try {

            Logs.info("The job({}/{}) is fired.", appName, jobClass);

            if (triggerType == JobTriggerType.DEFAULT){
                // refresh the job fire time if triggered by scheduler
                asyncExecutor.submit(new RefreshJobFireTimeTask(appName, jobClass, context));
            }

            if (!canRunJobInstance(appName, jobClass)){
                return;
            }

            // job is running
            jobSupport.updateJobStateDirectly(appName, jobClass, JobState.RUNNING);

            // create the job instance and shards
            instance = createInstanceAndShards(jobDetail, triggerType);

            // trigger the clients to pull shards
            jobSupport.triggerJobInstance(appName, jobClass, instance);

            // blocking until all shards to be finished or timeout
            Long timeout = jobDetail.getConfig().getTimeout();
            timeout = timeout == null ? 0L : timeout;
            JobInstanceWaitResp finishResp = jobSupport.waitingJobInstanceFinish(appName, jobClass, instance.getId(), timeout);
            if (finishResp.isSuccess()){
                // job instance is finished successfully
                // publish job finish event
                eventDispatcher.publish(new JobFinishedEvent(instance.getJobId(), instance.getId()));
            } else if (finishResp.isTimeout()){
                // job instance is timeout
                eventDispatcher.publish(new JobTimeoutEvent(instance.getJobId(), instance.getId(), buildJobTimeoutDetail(instance)));
            }

            // maybe now the job is paused, stopped, ..., so need to expect the job state
            jobSupport.updateJobStateSafely(appName, jobClass, JobState.WAITING);

            // job has finished
        } catch (JobStateTransferInvalidException e){
            // job state transfer error
            Logs.warn("failed to update job state(instances={}), cause: {}.", instance, e.toString());
        } catch (JobInstanceCreateException e){
            // handle when job instance create failed
            String cause = Throwables.getStackTraceAsString(e);
            Logs.error("failed to create job instance when execute job(jobDetail={}, instance={}), cause: {}",
                    jobDetail, instance, cause);
            handleJobExecuteFailed(jobDetail, instance, appName, jobClass, cause);
        } catch (Exception e){
            // handle other exceptions
            String cause = Throwables.getStackTraceAsString(e);
            Logs.error("failed to execute job(jobDetail={}, instance={}), cause: {}",
                    jobDetail, instance, cause);
            handleJobExecuteFailed(jobDetail, instance, appName, jobClass, cause);
        }
    }