jav后台生成Josn递归嵌套的demo，生成数据格式： [{"childMenu":[{"childMenu":[],"menuName":"子级1_1","parentId":1,"pid":3,"position":1},{"childMenu":[{"childMenu":[],"menuName":"子级1_2_1","parentId":4,"pid":5,"position":2}],"menuName":"子级1_2","parentId":1,"pid":4,"position":2}],"menuName":"父级1","parentId":0,"pid":1,"posit