Sometime this month builds in TravisCI started failing when you have something like this in your .travis.yml file:
jdk: - oraclejdk8
The error looks like this:
Installing oraclejdk8 ... install-jdk.sh 2019-07-17 Expected feature release number in range of 9 to 14, but got: 8
To fix this, assuming you want to keep testing with java 8 and not another version of java, you can switch to openjdk8 and build will start to pass:
jdk: - openjdk8