public VerifierContentProvider() {
   // TODO remove job from JobPool when it has finished.
   // for now, we just use unique names.
   String jobName = BASE_JOBNAME + " " + StringTool.unique(BASE_JOBNAME); // $NON-NLS-1$
   job = new DataLoader(jobName);
   globalJob = job;
   if (JobPool.getJobPool().getJob(job.getJobname()) == null) {
     JobPool.getJobPool().addJob(job);
   }
   job.addListener(this);
 }
 @SuppressWarnings("unchecked")
 public Object[] getElements(Object parent) {
   Object result = job.getData();
   if (result == null) {
     JobPool.getJobPool().activate(job.getJobname(), Job.LONG);
     return new String[] {Messages.ExterneDokumente_loading};
   } else {
     if (result instanceof List) {
       return ((List) result).toArray();
     } else if (result instanceof String) {
       return new Object[] {result};
     } else {
       return null;
     }
   }
 }