Firestore security rule MapDiff methods on nested object

Question

I am curious how MapDiff methods work on nested object

for example addedKeys, for top level only object

{"a":1}.diff({}).addedKeys() == ["a"].toSet()

this is how it works

but what about nested object?

{"a":{"b":"1"},"c":"2"}.diff({}).addedKeys() == [????].toSet()

and is the behaviour same on affectedKeys, changedKeys, removedKeys and unchangedKeys?

Answer 1

ok, I use rules.debug and found the answer

in the log, it prints

set_value {
  values {
    string_value: "a"
  }
  values {
    string_value: "c"
  }
}

so basically {"a":{"b":"1"},"c":"2"}.diff({}).addedKeys() == ["a","c"].toSet()

it ignores nested property