Output of the script https://github.com/imotov/elasticsearch-test-scripts/blob/master/array_in_source.sh

output.json

{
  "took" : 1,
  "timed_out" : false,
  "_shards" : {
    "total" : 5,
    "successful" : 5,
    "failed" : 0
  },
  "hits" : {
    "total" : 3,
    "max_score" : null,
    "hits" : [ {
      "_index" : "test-idx",
      "_type" : "doc",
      "_id" : "1",
      "_score" : null,
      "fields" : {
        "my_field" : [ "bar", "baz" ]
      },
      "sort" : [ "doc#1" ]
    }, {
      "_index" : "test-idx",
      "_type" : "doc",
      "_id" : "2",
      "_score" : null,
      "fields" : {
        "my_field" : [ "bar" ]
      },
      "sort" : [ "doc#2" ]
    }, {
      "_index" : "test-idx",
      "_type" : "doc",
      "_id" : "3",
      "_score" : null,
      "fields" : {
        "my_field" : "foo"
      },
      "sort" : [ "doc#3" ]
    } ]
  }
}