code: private ChildTaskContainer getParentTask(String wbs)
     {
        ChildTaskContainer result;
        String parentWbs = getParentWBS(wbs);
        if (parentWbs == null)
        {
           result = m_projectFile;
        }
        else
        {
           result = m_taskMap.get(parentWbs);
        }
        return result;
     }
docs: Retrieve the parent task based on its WBS.
  
  @param wbs parent WBS
  @return parent task