versionCodename property
A lower-case string identifying the operating system release code name, excluding any OS name information or release version, and suitable for processing by scripts or usage in generated filenames.
The codename contains no spaces or other characters outside of 0–9, a–z, '.', '_' and '-'.
Examples: 'buster', 'xenial'.
This field is optional and may be null on some systems.
Implementation
final String? versionCodename;