title: quartz.net thread was being aborted
body: <p>I'm using Quartz.net to create cron scheduled task in my Windows Service. 
  I got an ThreadAbortedException that I can't figure out why.
  It's appening when I'm trying to get the default scheduler. I red that I need to Shutdown my scheduler, which I did, but it does not fix the problem. 
  My function is called in a thread, but I don't think it really matters.<br>
  Here is my code.</p>
  
  <pre><code>public ITrigger InitCronJob(Type jobClass, string pattern = null) {
          ITrigger trigger = null;
          try {
              this.factories.GetLoggerFactory()
                  .Log($"Started cron job {jobClass.Name} on {DateTime.Now.ToString(LoggerFactory.dateFormat)}",
                      LogSeverity.Info);
              if (!factories.GetFolderFactory().getConfigFile().ContainsKey("cronPattern") &amp;&amp; pattern == null) {
                  throw new NoDefinedCronPattern("There is no cron pattern defined in the config.");
              }
              if (this.defaultScheduler == null) {
                  this.defaultScheduler = StdSchedulerFactory.GetDefaultScheduler(); // problem seams to be here.
              }
  
              IJobDetail job = JobBuilder.Create(jobClass).Build();
              trigger = TriggerBuilder.Create()
                  .WithIdentity("myJob - " + jobClass.Name + " - " + Guid.NewGuid().ToString(), "myJob")
                  .WithCronSchedule(pattern ?? factories.GetFolderFactory().getConfigFile()["cronPattern"])
                  .StartAt(DateTime.UtcNow)
                  .WithPriority(1)
                  .Build();
              this.defaultScheduler.ScheduleJob(job, trigger);
              this.defaultScheduler.Start();
          }
          finally {
              defaultScheduler?.Shutdown(true);
          }
  
          return trigger;
      }
  </code></pre>