OptionOrNull

Represents either a value, a missing field, or a null field Normally you would only need Option but this type exists for use with APIs that make a distinction between a json field being null and being missing altogether

Ensure you set null_as_undefined and empty_encode_as_null to false in your json_options eg: core.json_with_options { empty_encode_as_null: Bool.false, null_as_undefined: Bool.false }