Elasticsearch sort inside top_hits aggregation - elasticsearch

Question

I have an index of messages where I store messageHash for each message too. I also have many more fields along with them. There are multiple duplicate message fields in the index e.g. "Hello". I want to retrieve unique messages.
Here is the query I wrote to search unique messages and sort them by date. I mean the message with the latest date among all duplicates is what I want
to be returned.
{
"query": {
"bool": {
"must": {
"match_phrase": {
"message": "Hello"
}
}
}
},
"sort": [
{
"date": {
"order": "desc"
}
}
],
"aggs": {
"top_messages": {
"terms": {
"field": "messageHash"
},
"aggs": {
"top_messages_hits": {
"top_hits": {
"sort": [
{
"date": {
"order": "desc"
}
},
"_score"
],
"size": 1
}
}
}
}
}
}
The problem is that it's not sorted by date. It's sorted by doc_count. I just get the sort values in the response, not the real sorted results. What's wrong? I'm now wondering if it is even possible to do it.
EDIT:
I tried subsituting "terms" : { "field" : "messageHash", "order" : { "mydate" : "desc" } } , "aggs" : { "mydate" : { "max" : { "field" : "date" } } } for "terms": { "field": "messageHash" } but I get:
{
"error" : {
"root_cause" : [
{
"type" : "parsing_exception",
"reason" : "Found two sub aggregation definitions under [top_messages]",
"line" : 1,
"col" : 412
}
],
"type" : "parsing_exception",
"reason" : "Found two sub aggregation definitions under [top_messages]",
"line" : 1,
"col" : 412
},
"status" : 400
}