Aggregation query with nested field returns garbage

[galkk]

Aggregation query returns very strange results.
Expected results: either clear error message that the query is not supported or correct results

GET /_opendistro/_sql
{
  "query": """
    SELECT e.name, COUNT(p.title)
    FROM employess_with_missing e, e.projects p
  """
}

returns

{
  "took" : 2,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 5,
      "relation" : "eq"
    },
    "max_score" : null,
    "hits" : [ ]
  },
  "aggregations" : {
    "projects.title@NESTED" : {
      "doc_count" : 3,
      "COUNT(nested=com.amazon.opendistroforelasticsearch.sql.parser.NestedType@1f3b445b)" : {
        "value" : 0
      }
    }
  }
}

Expected result:
Bob Smith: 0
Ian Smith: 0
Joh Smith: 0
Susan: 1
Jane: 1

The results with GROUP BY do not make sense as well, although given that we work with nested fields then I'm not sure that we should have aggregation there, so it's debatable

GET /_opendistro/_sql
{
  "query": """
    SELECT e.name, COUNT(p.title)
    FROM employess_with_missing e, e.projects p
    GROUP BY e.name
  """
}

Test data

DELETE employess_with_missing

PUT employess_with_missing
{
    "aliases" : { },
    "mappings" : {
      "properties" : {
        "age" : {
          "type" : "long"
        },
        "name" : {
          "type" : "text",
          "fields" : {
            "keyword" : {
              "type" : "keyword",
              "ignore_above" : 256
            }
          }
        },
        "title" : {
          "type" : "text",
          "fields" : {
            "keyword" : {
              "type" : "keyword",
              "ignore_above" : 256
            }
          }
        },
        "projects": {
          "type": "nested"
        }
      }
    }
}

GET /employess_with_missing

PUT /employess_with_missing/_doc/1?pretty
{
"name": "Bob Smith"
}

PUT /employess_with_missing/_doc/2?pretty
{
"name": "Ian Smith", "title": null, "age": null,
 "projects" :null
}


PUT /employess_with_missing/_doc/3?pretty
{
"name": "John Smith", "title": null, "age": null,
 "projects" : []
}

PUT /employess_with_missing/_doc/4?pretty
{
"name": "Susan Smith", "title": "Dev Mgr", "age": 33,
 "projects" : [
   {
      "name": "War games #1",
      "start_date": "2017-05-01"
   }
   ]
}

PUT /employess_with_missing/_doc/5?pretty
{
"name": "Jane Smith", "title": "Software Eng 2", "age": 25,
 "projects" : [
   {
      "name": "War games #1",
      "start_date": "2017-05-01",
      "end_date": "2018-06-20"
   },
   {
      "name": "Peace games #1",
      "start_date": "2018-06-21"
   }   
   ]
}