Let users specify unique function keys using delay.MustRegister

[KaylaNguyen]

No description provided.

[zevdg]

I'm a little confused. At a glance, this looks like the same exact change as #261 just on the master branch instead of qa and squashed to 1 commit. Is that right? If so, this SGTM. We made this change in a totally backwards compatible way so backporting it to master makes total sense.

Since we already reviewed the code in #261, it seems like the approver for this CL should be verifing that you've backported the fix from qa to master correctly. If your team has a process for this, I don't know what it is, so I can't verify that you've followed it correctly. If they don't have a process and you're flying by the seat of your pants, that's ok for now, but you should document how you did this one as a baseline and I can at least review that process.

[KaylaNguyen]

Yes, this commit is an exact replica of #261 but to master branch. We don't have a process for this so I'm just porting this change manually.

[zevdg]

Did you run some git commands to create this commit? I'd feel much better about approving this if it was created by a git merge --squash. If not, could you try recreating this change using git merge --squash?

[KaylaNguyen]

TIL, thanks!
I did
→ git checkout master
→ git merge --squash delaypkg
→ git commit ....
→ git checkout delaypkg-master
→ git merge qa-upstream

A bit roundabout but I think that works.