Can the minus key (modified) be used as an Editor Command keyboard shortcut?

I don’t know if this is a bug, or there’s a way already to do what I want, but this fails:

"shortcut": "cmd-ctrl--"

I want to use the minus/hyphen key in that shortcut. (I also tried backslash-escaping the final “-” as well as using the name “minus” and “hyphen” to no avail.)

My extension DOES work with a letter, like the following, so everything is fine except the shortcut.

"shortcut": "cmd-ctrl-i"

(The extension’s purpose is to take selected mixed-case text (like a filename or title) and change it to all lowercase with no punctuation except hyphens between the words… so “Why? Why Not!” becomes “why-why-not”. Useful for making URL slugs etc. So the hyphen key is the logical choice.)

Thanks in advance!