We currently maintain an Ubuntu Bionic (current) and Ubuntu Xenial (legacy) build job on Travis CI. It looks like a few languages have moved forward and dropped some of the older language level support on Xenial.
I'd like to suggest we start treating the xenial build job as one that tests the oldest compatible version of a language we can find. As an example, dart-1.x is no longer distributed by the dart team. They now distribute v2.0 through v2.4. Further, if a language level is already being tested on Bionic and we cannot select an older one for Xenial, we should disable the language on Xenial by removing it from the Dockerfile. This will make that build job faster. Thanks, Jim
