The only encoding version that exists is `1`. There is no need to have
multiple constants for that version across different packages. Because
there is only one version, `GenerateVolID()` does not really require it,
and it can use a default version.
If there is a need in the future to support an other encoding version,
this can be revisited with a cleaner solution.
Signed-off-by: Niels de Vos <ndevos@ibm.com>
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