Unable To Split Json Array in Elasticsearch Query Response

Hi,
Not able to parse brand filed from below response. Logstash taking requests on port 31315
via http input plugin
json to be parsed:

{
"took": 2,
"timed_out": false,
"_shards": {
"total": 1,
"successful": 1,
"skipped": 0,
"failed": 0
},
"hits": {
"total": {
"value": 1,
"relation": "eq"
},
"max_score": 11.48834,
"hits": [
{
"_index": "rjilrepo",
"_type": "_doc",
"_id": "91150500",
"_score": 11.48834,
"_source": {
"brand": "LYF",
"model": "LS-5015",
"@timestamp": "2019-08-29T13:42:56.723Z",
"TAC": "91150500",
"DATA_GPRS": "1",
"jiolte": "true",
"jiovolte": "true",
"os": "Android",
"deviceType": "Smartphone",
"2G": "true",
"3G": "true",
"4G": "true",
"UICC.Sim Type": "MicroNano"
}
}
]
}
}

My Logstash Code below
input {
http {
host => "10.144.20.56"
port => 31315
codec => "json"

            }

}

filter {
json { source => "message" }

split {
field => "hits"
}

mutate {
add_field => {
"LocalizationId" => "%{[hits][total][value]}"
"Rel" => "%{[hits][total][relation]}"
"brand" => "%{[hits][hits][_source][brand]}"
}
remove_field => [ "[message]" ]
}
}

output {
file {
path => "/tmp/apicall.log"
}

  exec {command => "echo %{LocalizationId} %{Rel} %{brand} > /tmp/fffff"}

}

Thnks in advance...