Not sure if this would be a breaking change.

I think that'd be a breaking change now, and for very little benefit. Maybe adding an extra method or a parameter to them?

I disagree with the "very little benefit" part. By using lower case, the output is non-compliant and therefore incorrect.

I disagree with the "very little benefit" part. By using lower case, the output is non-compliant and therefore incorrect.

#7 would now break all the codes that rely on the lowercase ids that this code generates. I know at least two apps that use it such way, and their database is case sensitive.

If the code is only soft-compliant, I am willing to live with it.