Hi there. Thank you for creating this great piece of software.
I was looking at using it for creating appstream metadata for my application called wormhole-gui. When I entered the unique identifier for it (com.github.jacalz.wormhole-gui), it complained about hyphens not being allowed.

I know that websites allow hyphens (https://wi-fi.org) and I couldn’t find any information about hyphens not being allowed for unique software identifiers (or appID). Is this something that is specific to the appstream specification or am I just missing something obvious here? I would greatly appreciate if someone could clear up the situation for me :)