code: public Object[] getChildren(Object parent) {
  
      if (parent instanceof HadoopServer) {
        HadoopServer location = (HadoopServer) parent;
        location.addJobListener(this);
        Collection<HadoopJob> jobs = location.getJobs();
        return jobs.toArray();
      }
  
      return null;
    }
docs: /* @inheritDoc