code: public CmsGroup getParent(CmsDbContext dbc, String groupname) throws CmsException {
  
          CmsGroup group = readGroup(dbc, groupname);
          if (group.getParentId().isNullUUID()) {
              return null;
          }
  
          // try to read from cache
          CmsGroup parent = m_monitor.getCachedGroup(group.getParentId().toString());
          if (parent == null) {
              parent = getUserDriver(dbc).readGroup(dbc, group.getParentId());
              m_monitor.cacheGroup(parent);
          }
          return parent;
      }
docs: Returns the parent group of a group.<p>
  
  @param dbc the current database context
  @param groupname the name of the group
  
  @return group the parent group or <code>null</code>
  
  @throws CmsException if operation was not successful