Pipeline aggregation | Cumulative sum aggregation on a nested field

[mehtaanshul (Anshul Mehta)]

My Elasticsearch index mappings -

{
    "mappings": {
        "properties": {
            "timestamp": {
                "type": "date"
            },
            "detail": {
                "type": "nested",
                "properties": {
                    "attributes": {
                        "properties": {
                            "levelValue": {
                                "type": "text",
                                "fields": {
                                    "keyword": {
                                        "type": "keyword",
                                        "ignore_above": 256
                                    }
                                }
                            }
                        }
                    }
                }
            }
        }
    }
}

Possible values of levelValue -> A, B, C

A new document is created in my index whenever levelValue changes it's value

I want to create a time series graph which will show the levelValue of objects over time and I am trying to use cumulative sum query to achieve this.
and I cannot change my index mappings.

Query

{
        "size": 0,
        "aggs": {
            "updates_over_time": {
                "date_histogram": {
                    "field": "timestamp",
                    "calendar_interval": "day"
                }
            },
            "detail": {
                "nested": {
                    "path": "detail"
                },
                "aggs": {
                    "levelValue_updates": {
                        "terms": {
                            "field": "detail.attributes.levelValue.keyword"
                        }
                    },
                    "cumulative_levelValue_updates": {
                        "cumulative_sum": {
                            "buckets_path": "levelValue_updates"
                        }
                    }
                }
            }
        }
    }

I am getting the following error -

\"reason\":\"Validation Failed: 1: cumulative_sum aggregation [cumulative_levelValue_updates] must have a histogram, date_histogram or auto_date_histogram as parent;\"