Normal field alias no longer stored in the response.

[penghuo]

The normal filed with alias doesn't work as expected. e.g.

Query

POST _opendistro/_sql?
{
  "query": "SELECT address as key, age FROM sql_index_account WHERE address is not null limit 10"
}

Response

{
   ...
  "hits" : {
    ...
    "hits" : [
      {
        ....
        "_source" : {
          "address" : "171 Putnam Avenue",
          "age" : 39
        }
      }
    ]
  }
}

Expected Response

{
   ...
  "hits" : {
    ...
    "hits" : [
      {
        ....
        "_source" : {
          "key" : "171 Putnam Avenue",
          "age" : 39
        }
      }
    ]
  }
}

[arsen-es]

Didn't find a generic way for a fix, will keep looking, in the meantime asked elastic community as well:
https://discuss.elastic.co/t/rename-fields-in-the-search-output/196850

[dai-chen]

This is a same issue as #147 which we won't fix for now.