Elasticsearch query using Kibana does not work using Java Rest Client API

Question

Can someone help determine why a kibana query does not return hits when using the Elasticsearch Java Rest Client API.

I am currently using Elasticsearch/Kibana: 7.16.2 Elasticsearch Java Client: 6.6.2

I am reluctant to upgrade java client due to numerous Geometry related updates needed.

fields: mydatetime: timestamp of doc category: keyword field

We have 1000 or more records for each category a day.

I want an aggregation that shows categories by day and includes the first and last "date" for the category.

This query works in Kibana

GET /mycategories/_search

{
   "size":0,
   "aggregations":{
      "bucket_by_date":{
         "date_histogram":{
            "field":"mydatefield",
            "format":"yyyy-MM-dd",
            "interval":"1d",
            "offset":0,
            "order":{
               "_key":"asc"
            },
            "keyed":false,
            "min_doc_count":1
         },
         "aggregations":{
            "unique_categories":{
               "terms":{
                  "field":"category",
                  "size":10,
                  "min_doc_count":1,
                  "shard_min_doc_count":0,
                  "show_term_doc_count_error":false,
                  "order":[
                     {
                        "_count":"desc"
                     },
                     {
                        "_key":"asc"
                     }
                  ]
               },
               "aggregations":{
                  "min_mydatefield":{
                     "min":{
                        "field":"mydatefield"
                     }
                  },
                  "max_mydatefield":{
                     "max":{
                        "field":"mydatefield"
                     }
                  }
               }
            }
         }
      }
   }
}

The first record of the result...category1 and category2 for 2022 05 07 with min and max "mydatetime" for each category

{
  "took" : 0,
  "timed_out" : false,
  "_shards" : {
    "total" : 4,
    "successful" : 4,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 2593,
      "relation" : "eq"
    },
    "max_score" : null,
    "hits" : [ ]
  },
  "aggregations" : {
    "bucket_by_date" : {
      "buckets" : [
        {
          "key_as_string" : "2022-05-07",
          "key" : 1651881600000,
          "doc_count" : 2,
          "unique_missions" : {
            "doc_count_error_upper_bound" : 0,
            "sum_other_doc_count" : 0,
            "buckets" : [
              {
                "key" : "category1",
                "doc_count" : 1,
                "min_mydatefield" : {
                  "value" : 1.651967952E12,
                  "value_as_string" : "2022-05-07T13:22:17.000Z"
                },
                "max_mydatefield" : {
                  "value" : 1.651967952E12,
                  "value_as_string" : "2022-05-07T23:59:12.000Z"
                }
              },
              {
                "key" : "category2",
                "doc_count" : 1,
                "min_mydatefield" : {
                  "value" : 1.651967947E12,
                  "value_as_string" : "2022-05-07T03:47:23.000Z"
                },
                "max_mydatefield" : {
                  "value" : 1.651967947E12,
                  "value_as_string" : "2022-05-07T23:59:07.000Z"
                }
              }
            ]
          }
        },

I have successfully coded other, less complex aggregations without problems. However, i have not been able to get either an AggregationBuilder or WrapperQuery. Zero results are returned.

{"took":0,"timed_out":false,"_shards":{"total":0,"successful":0,"skipped":0,"failed":0},"hits":{"total":0,"max_score":0.0,"hits":[]}}

Before executing the query, i copy the SearchRequest.source() into Kibana, and it runs and returns the desired information.

Below is the AggregationBuilder code that seems to replicate my kibana query, but returns no results.

        AggregationBuilder aggregation =
                AggregationBuilders

                        .dateHistogram("bucket_by_date").format("yyyy-MM-dd")
                        .minDocCount(1)
                        .dateHistogramInterval(DateHistogramInterval.DAY)
                        .field("mydatefield")
                        .subAggregation(
                                AggregationBuilders
                                        .terms("unique_categories")
                                        .field("category")
                                        .subAggregation(
                                                AggregationBuilders
                                                        .min("min_mydatefield")
                                                        .field("mydatefield")
                                        )
                                        .subAggregation(
                                                AggregationBuilders
                                                        .max("max_mydatefield")
                                                        .field("mydatefield")
                                        )
                        );