@kayrus Thanks! Two minor changes to make and one change modifying the main Volume struct - let me know if you have any questions.

Also, some general info for you and for others researching in the future: I'm kicking around the idea of squashing all of the "Ext" structs into the main resource structs.

This change recently began with microversions (#1854) in order to prevent lots of small microversion updates from becoming unmanageable, but I'm thinking about doing it for all types of extensions. This PR is notable because the amendments to the CreateOpts are both from an extension (backups) and a microversion, so we'll leave this as-is for now.

Historically, the "Ext" structs provided a large design value with Gophercloud: it allowed us to model the OpenStack API in a very composable and modular way, helping us make Gophercloud flexible and extendible. But after 4-5 years of working on Gophercloud, I'm almost confident that squashing all extensions into the main resource structs won't do any harm.

I'm not quite ready to make this change yet, but I'm considering it.

/cc @ozerovandrei

@kayrus Thanks for continuing with this. Two minor changes and I think this should be good to go.

LGTM - thank you!