old_contents: var demoList = [{
      "name": "Castle",
      "path": "demo/castle.oa"
  }, {
      "name": "Chair",
      "path": "demo/chair.oa"
  }, {
      "name": "Hourse",
      "path": "demo/hourse.oa"
  }, {
      "name": "Bath",
      "path": "demo/bath.oa"
  }, {
      "name": "Yahoo",
      "path": "demo/yahoo.oa"
  }, {
      "name": "Nowday",
      "path": "demo/nowday.oa"
  }];
new_contents: var demoList = [{
      "name": "Castle",
      "path": "demo/castle.oa"
  }, {
      "name": "Chair",
      "path": "demo/chair.oa"
  }, {
      "name": "Hourse",
      "path": "demo/hourse.oa"
  }, {
      "name": "Bath",
      "path": "demo/bath.oa"
  }, {
      "name": "Yahoo",
      "path": "demo/yahoo.oa?v2"
  }, {
      "name": "Nowday",
      "path": "demo/nowday.oa"
  }];
subject: update demo list