ElasticSearch Nested Search Analyzer not working

Question

Index Creation

I'm creating index with nested property and assigning analyzers to it both index and search time as follows.

PUT /test_index_pasu
{
  "settings": {
    "analysis": {
      "analyzer": {
        "keyword_analyzer": {
          "tokenizer": "keyword",
          "filter": [
            "lowercase",
            "asciifolding"
          ]
        }
      }
    }
  },
  "mappings": {
    "properties": {
      "groups": {
        "type": "nested",
        "properties": {
          "key": {
            "type": "keyword"
          },
          "values": {
            "type": "text",
            "analyzer": "keyword_analyzer",
            "search_analyzer": "keyword_analyzer",
            "fields": {
              "keyword": {
                "type": "keyword"
              }
            }
          }
        }
      }
    }
  }
}

When I try to query (search filter) search time analyzer wasn't honored. I tried to check the GET mapping, it is missing search_analyzer anything specific needs to be done for nested search analyzer.?

Get Mapping Index

{
  "test_index_pasu": {
    "mappings": {
      "properties": {
        "groups": {
          "type": "nested",
          "properties": {
            "key": {
              "type": "keyword"
            },
            "values": {
              "type": "text",
              "fields": {
                "keyword": {
                  "type": "keyword"
                }
              },
              "analyzer": "keyword_analyzer"
            }
          }
        }
      }
    }
  }
}