targetOsVersion property
New platform version of the OS image being downloaded and applied.
It is only set when update status is UPDATE_STATUS_DOWNLOAD_IN_PROGRESS or UPDATE_STATUS_NEED_REBOOT. Note this could be a dummy "0.0.0.0" for UPDATE_STATUS_NEED_REBOOT for some edge cases, e.g. update engine is restarted without a reboot.
Implementation
core.String? targetOsVersion;