Spam instead of Junk folder

Traditionally I have used 'Spam' as the folder name for all those emails that get tagged as, well Spam.

But it seems that the standard is now 'Junk' as from 15-mailboxes.conf

 # Space separated list of IMAP SPECIAL-USE attributes as specified by
 # RFC 6154: \All \Archive \Drafts \Flagged \Junk \Sent \Trash
 #special_use =

If I have in local.conf

# 15-mailboxes.conf

namespace inbox { mailbox Spam { special_use = \Junk } }

This would auto make Spam, but:

Would Junk (and all the others specified in 15-mailboxes.conf) still get created?

What actually controls which folders get created?