code: public ICommonsSet <JobKey> getJobKeys (final GroupMatcher <JobKey> matcher) throws SchedulerException
    {
      validateState ();
  
      return m_aResources.getJobStore ().getJobKeys (_getOrDefault (matcher));
    }
docs: <p>
  Get the names of all the <code>{@link com.helger.quartz.IJob}s</code> in
  the matching groups.
  </p>