如何使用Java手动压缩Elasticsearch嵌套的JSON文档？

Question

我想为我的Elasticsearch文档结构生成一些文档。问题是我在我的索引中存储了嵌套的JSON，但我想记录Elasticsearch正在生成的flattend JSON格式¹。

有没有办法将此JSON压扁，类似于Elasticsearch使用ES Java API生成的方式？

如果可能，我不想为此任务启动Elasticsearch。

示例JSON：

{
  "title": "Nest eggs",
  "body":  "Making your money work...",
  "tags":  [ "cash", "shares" ],
  "comments": [ 
    {
      "name":    "John Smith",
      "comment": "Great article",
      "age":     28,
      "stars":   4,
      "date":    "2014-09-01"
    },
    {
      "name":    "Alice White",
      "comment": "More like this please",
      "age":     31,
      "stars":   5,
      "date":    "2014-10-22"
    }
  ]
}

一旦Elasticsearch将其展平，该文档将如下所示。

{
  "title":            [ eggs, nest ],
  "body":             [ making, money, work, your ],
  "tags":             [ cash, shares ],
  "comments.name":    [ alice, john, smith, white ],
  "comments.comment": [ article, great, like, more, please, this ],
  "comments.age":     [ 28, 31 ],
  "comments.stars":   [ 4, 5 ],
  "comments.date":    [ 2014-09-01, 2014-10-22 ]
}

[1] https://www.elastic.co/guide/en/elasticsearch/guide/current/nested-objects.html