code: void migrateGroup(Node oldGroupNode) throws Exception
     {
        String groupName = oldGroupNode.getName();
        String desc = utils.readString(oldGroupNode, GroupProperties.JOS_DESCRIPTION);
        String label = utils.readString(oldGroupNode, GroupProperties.JOS_LABEL);
        String parentId = utils.readString(oldGroupNode, MigrationTool.JOS_PARENT_ID);
  
        GroupImpl group = new GroupImpl(groupName, parentId);
        group.setDescription(desc);
        group.setLabel(label);
  
        Group parentGroup = findGroupById(group.getParentId());
  
        if (findGroupById(group.getId()) != null)
        {
           removeGroup(group, false);
        }
  
        addChild(parentGroup, group, false);
     }
docs: Method for group migration.
  @param oldGroupNode
  the node where group properties are stored (from old structure)