code: private void addHours(MpxjTreeNode parentNode, ProjectCalendarDateRanges hours)
     {
        for (DateRange range : hours)
        {
           final DateRange r = range;
           MpxjTreeNode rangeNode = new MpxjTreeNode(range)
           {
              @Override public String toString()
              {
                 return m_timeFormat.format(r.getStart()) + " - " + m_timeFormat.format(r.getEnd());
              }
           };
           parentNode.add(rangeNode);
        }
     }
docs: Add hours to a parent object.
  
  @param parentNode parent node
  @param hours list of ranges