Since this has been merged in 2.119, my Jenkins installation is constantly showing the "Jenkins root URL seems to be invalid. It is required for the proper operation of many Jenkins features like email notifications, PR status update, and environment variables such as BUILD_URL." notification.
I have tried modified the URL setting to a completely different value, and then back to the correct value to ensure that it is definitely set, yet this message continues to display (even after a Jenkins restart).
The configured URL is definitely correct. I'm guessing there's some extra check being performed which makes Jenkins believe it to be incorrect - most likely something related to the docker / nginx setup I've got going on. However, I feel like there should be a simple way of confirming to Jenkins that yes, the URL as configured is the correct one for it to be using and to stop prompting about it.