Fix Task deserialization

{
  "entity-type": "task",
  "id": "bf8b6a82-495b-47c5-a327-04a57ef995d0",
  "name": "wf.serialDocumentReview.chooseParticipants",
  "workflowInstanceId": "00ea5eb4-d591-4cd6-b76c-e73d1f3a99bd",
  "workflowModelName": "SerialDocumentReview",
  "state": "ended",
  "directive": "wf.serialDocumentReview.pleaseSelect",
  "created": "2018-06-11T14:32:38.912Z",
  "dueDate": "2018-06-16T14:32:38.840Z",
  "nodeName": "Task38e",
  "targetDocumentIds": [
    {
      "id": "62c02cf6-4891-400d-a687-e544fc081706"
    }
  ],
  "actors": [
    {
      "id": "Administrator"
    }
  ],
  "comments": [
    {
      "author": "Administrator",
      "text": "comment",
      "date": "2018-06-11T14:32:39.126Z"
    }
  ],
  "variables": {
    "comment": "comment",
    "participants": [
      "user:Administrator"
    ],
    "validationOrReview": "simpleReview"
  },
  "taskInfo": {
    "taskActions": [
      {
        "name": "cancel",
        "url": "http://localhost:8080/nuxeo/api/v1/task/bf8b6a82-495b-47c5-a327-04a57ef995d0/cancel",
        "label": "wf.serialDocumentReview.cancel"
      },
      {
        "name": "start_review",
        "url": "http://localhost:8080/nuxeo/api/v1/task/bf8b6a82-495b-47c5-a327-04a57ef995d0/start_review",
        "label": "wf.serialDocumentReview.startReview"
      }
    ],
    "layoutResource": {
      "name": "Task38e@taskLayout",
      "url": "http://localhost:8080/nuxeo/site/layout-manager/layouts/?layoutName=Task38e@taskLayout"
    },
    "schemas": [
      {
        "name": "dublincore",
        "url": "http://localhost:8080/nuxeo/api/v1/config/schemas/dublincore"
      },
      {
        "name": "var_global_Task38e",
        "url": "http://localhost:8080/nuxeo/api/v1/config/schemas/var_global_Task38e"
      },
      {
        "name": "route_node",
        "url": "http://localhost:8080/nuxeo/api/v1/config/schemas/route_node"
      },
      {
        "name": "var_Task38e",
        "url": "http://localhost:8080/nuxeo/api/v1/config/schemas/var_Task38e"
      }
    ]
  }
}