code: public void setGroup (final String group)
    {
      if (group != null && group.trim ().length () == 0)
        throw new IllegalArgumentException ("Group name cannot be an empty string.");
  
      if (group == null)
        m_sGroup = IScheduler.DEFAULT_GROUP;
      else
        m_sGroup = group;
      m_aKey = null;
    }
docs: <p>
  Set the name of this <code>Trigger</code>.
  </p>
  
  @param group
  if <code>null</code>, Scheduler.DEFAULT_GROUP will be used.
  @exception IllegalArgumentException
  if group is an empty string.