Default Ubuntu dist just changed to Focal? Need a libssl 1.x

The Build Environment Overview docs continue to say that Xenial (16.04) is the default, yet we have just (part-way through our morning) experienced builds failing after an apparent shift of the default from Xenial to Focal. Yes, I know that Xenial is no longer in LTS from Ubuntu, but a heads up to prepare and test for this would have been nice.

The issue with the change, other than the unexpected surprise and disruption, is that we have components that rely upon libssl 1.x to function, and that isn’t there in the Focal installation. What’s the best way to rectify that?