When updating an Issue in Atlassian JIRA using a Groovy Script Listener, the fields will become out-of-sync with what the GUI says they equal. (Resolution set to Duplicate but the GUI still says it is Unresolved etc) By performing the updates within a new thread, the GUI updates as well. I have no idea why...

Update JIRA Issue Groovy Listener

class SampleIssueListener extends AbstractIssueEventListener {
 
    @Override
    void workflowEvent(IssueEvent event) {
      //Prepare and Validate update/transition
      //Create a worker thread that waits for 2 seconds before performing the transition.
      ScheduledExecutorService worker = Executors.newSingleThreadScheduledExecutor();
      Runnable runnableUpdate = new Runnable() {
      	@Override
      	public void run() {				
      		//Perform Update/Transition
      		//Preparation needs to occur outside of this Runnable or you will encounter permission issues
      	}
      };
      
      worker.schedule(runnableUpdate, 2, TimeUnit.SECONDS);
    }
}