Travis CI builds are failing with an error Expected feature release number in range of 9 to 14, but got: 8
This has something to do with a change on Travis CI end and Java 8 to build the project.
Change the build image to use an older version of Ubuntu (Trusty)
Use openjdk8 instead of oraclejdk8
All of this is configurable in the .travis.yml file.
Oracle JDK 8 seems to be available in Trusty: https://docs.travis-ci.com/user/reference/trusty/#jvm-clojure-groovy-java-scala-images
While Xenial (the default distro) only includes OpenJDK8: https://docs.travis-ci.com/user/reference/xenial/#jvm-clojure-groovy-java-scala-support
This must have changed sometime after setting up the builds.