Control returned fields of nested object

[elastic_guy (guy)]

Hi,
let's say I have a document with a nested object inside, for example:

"mappings": {
  "typeX": {
    "properties": {
      "array_of_things": {
        "type": "nested",
        "properties": {
          "long_propertyA": {
            "type": "long"
          },
          "range_propertyB": {
            "type": "integer_range"
          }
        }
      }
    }
  }
}

as you can see "array_of_things" is a nested object, containing an array of objects, where, each of them has 2 properties - long property & range property..

I am trying to understand if it's possible to read the upper object and neglect the "range" field for example..
it's a big field, and not relevant for some of our queries, and therefor I would like to neglect it from some of my read operations..

now, I know that there is a "fetch source" API that I can use it to specify include and exclude properties of documents, but I couldn't find any documentation on how to use it on nested object's properties.

appreciate your help,
Thanks