How to duplicate a property in array items inside a dictionary

Working with Data
1

I have a Project collection that stores versions keyed by the version number, and each version has a config which has an array of packages.

A document looks like this:

{
    "_id" : 12345,
    "versions" : {
        "1" : {
            "status" : "OUTDATED",
            "config" : {
                "pkgs" : [
                    { "id" : 1, "name" : "pkgX" },
                    { "id" : 2, "name" : "pkgY" }
                ]
            }
        },
        "2" : {
            "status" : "LIVE",
            "config" : {
                "pkgs" : [
                    { "id" : 1, "name" : "pkgZ" }
                ]
            }
        }
    }
}

If it helps, in Java this is mapped as follows:

class Project {
    Map<Integer, Version> versions;

class Version {
    Config config;

class Config {
    List<Pkg> pkgs

class Pkg {
    int id;

I need to add a new sequence property to each package, setting its value to the value of the id.
Example: the item { "id" : 2, "name" : "pkgY" } should become { "id" : 2, "sequence" : 2, "name" : "pkgY" }

In addition, my update should not break when the versions property of the root document does not exist and when the pkgs property of the config does not exist.

Thanks community in advance.