如何用Jolt Spec实现数组元素非空校验及字段赋值与JSON转换？

途经点列表（way_points）中仅包含position=1的元素，或同时包含position=1和position=2的元素。转换规则如下：

• 若存在position=2且预计到达时间（eta）不为null，则messageType赋值为'STOP_ETA_UPDATE'；
• 若不存在position=2，则messageType赋值为'TRACKING_UPDATE'。

输入输出示例 #

输入JSON1 #

{
  "task": {
    "external_id": "2023-03-22-13-15-18-184000",
    "way_points": [
      {
        "address": "Warminster Road",
        "position": 1,
        "eta": null
      },
      {
        "address": "7 John Rennie Close",
        "position": 2,
        "eta": "2023-03-22T13:33:54.827Z"
      }
    ]
  },
  "webhook_type": "driver_on_the_way",
  "merchant_id": 60470
}

输出JSON1 #

{
  "shipper" : 60470,
  "shipmentId" : "externalId",
  "messages" : [ {
    "eta" : "2023-03-22T13:33:54.827Z",
    "messageType" : "STOP_ETA_UPDATE",
    "message" : "driver_on_the_way"
  } ]
}

输入JSON2 #

{
  "task": {
    "external_id": "2023-03-22-13-15-18-184000",
    "way_points": [
      {
        "address": "Warminster Road",
        "position": 1,
        "eta": null
      }
    ]
  },
  "webhook_type": "driver_on_the_way",
  "merchant_id": 60470
}

输出JSON2 #

{
  "shipper" : 60470,
  "shipmentId" : "externalId",
  "messages" : [ {
    "eta" : "2023-03-22T13:33:54.827Z",
    "messageType" : "TRACKING_UPDATE",
    "message" : "driver_on_the_way"
  } ]
}

现有Jolt Spec #

[
  {
    "operation": "shift",
    "spec": {
      "task": {
        "way_points": {
          "*": {
            "position": {
              "2": {
                "eta": {
                  "|null": null,
                  "#TRACKING_UPDATE": "messageType1",
                  "*": {
                    "#STOP_ETA_UPDATE": "messageType1"
                  }
                }
              }
            }
          }
        }
      }
    }
  }
]

请完善上述Jolt Spec，实现符合需求的JSON转换逻辑。

内容的提问来源于stack exchange，提问作者rashmi n