As was apparently done for the above build, a possible workaround is to switch to xcode9.4.
I’m not sure how long that will remain the case, however. I’m assuming since there was a change that these are not immutable images, and that they may be rebuilt and get the newer java version as a result ?
Update: indeed, the xcode9.4 image is now also affected and uses java 13. I don’t think it’s reasonable to expect any macOs testing to rely on the latest, just-released (non-LTS!) JDK version.
Edit - build example: https://travis-ci.org/miraisolutions/xlconnect/jobs/626577971