[BUG] Date formats are not recognized for nested type fields

[GumpacG]

What is the bug?
Date formats are not formatted for nested type.

How can one reproduce the bug?
Steps to reproduce the behavior:

1. Load mappings file:

{
  "mappings": {
    "properties": {
      "message": {
        "type": "nested",
        "properties": {
          "info": {
            "type": "keyword",
            "index": "true"
          },
          "author": {
            "type": "keyword",
            "fields": {
              "keyword": {
                "type": "keyword",
                "ignore_above": 256
              }
            },
            "index": "true"
          },
          "dayOfWeek": {
            "type": "long"
          },
          "date": {
            "type": "date",
            "format": "date"
          },
          "time": {
            "type": "date",
            "format": "hour_minute_second"
          },
          "timestamp": {
            "type": "date",
            "format": "date_time"
          }
        }
      },
      "comment": {
        "type": "nested",
        "properties": {
          "data": {
            "type": "keyword",
            "index": "true"
          },
          "likes": {
            "type": "long"
          }
        }
      },
      "myNum": {
        "type": "long"
      },
      "someField": {
        "type": "keyword",
        "index": "true"
      }
    }
  }
}

3. Load data

{"index":{"_id":"1"}}
{"message":{"info":"a","author":"e","dayOfWeek":1,"date":"1984-04-12","time":"08:47:52","timestamp":"1984-04-12T08:47:52.000Z"},"comment":{"data":"ab","likes":3},"myNum":1,"someField":"b"}
{"index":{"_id":"2"}}
{"message":{"info":"b","author":"f","dayOfWeek":2,"date":"2023-05-30","time":"06:50:16","timestamp":"2023-05-30T06:50:16.000Z"},"comment":{"data":"aa","likes":2},"myNum":2,"someField":"a"}
{"index":{"_id":"3"}}
{"message":{"info":"c","author":"g","dayOfWeek":1,"date":"1974-12-11","time":"01:25:02","timestamp":"1974-12-11T01:25:02.000Z"},"comment":{"data":"aa","likes":3},"myNum":3,"someField":"a"}
{"index":{"_id":"4"}}
{"message":[{"info":"c","author":"h","dayOfWeek":4,"date":"1995-03-17","time":"08:24:02","timestamp":"1995-03-17T08:47:52.000Z"},{"info":"a","author":"i","dayOfWeek":5,"date":"2009-03-17","time":"11:58:08","timestamp":"2009-03-17T11:58:08.000Z"}],"comment":{"data":"ab","likes":1},"myNum":4,"someField":"b"}
{"index":{"_id":"5"}}
{"message": [{"info":"zz","author":"zz","dayOfWeek":6,"date":"2015-03-03","time":"06:51:55","timestamp":"2015-03-03T06:51:55.000Z"}],"comment":{"data":["aa","bb"],"likes":10},"myNum":[3,4],"someField":"a"}

5. Run the query SELECT nested(message.timestamp) FROM nested_date
6. See result:

+--------------------------+
| nested(message.timestamp)|
|--------------------------|
| 1984-04-12T08:47:52.000Z |
| 2023-05-30T06:50:16.000Z |
| 1974-12-11T01:25:02.000Z |
| 1995-03-17T08:47:52.000Z |
| 2009-03-17T11:58:08.000Z |
| 2015-03-03T06:51:55.000Z |
+--------------------------+

What is the expected behavior?
It should format the date string based on the format specified in the mappings file. Result should be:

+---------------------+
| message.timestamp   |
|---------------------|
| 1984-04-12 08:47:52 |
| 2023-05-30 06:50:16 |
| 1974-12-11 01:25:02 |
| 1995-03-17 08:47:52 |
| 2015-03-03 06:51:55 |
+---------------------+

What is your host/environment?

• Version 2.8

Do you have any additional context?
Root cause may be that nested function gets data from the hits and ignores parsing of date string.