<Unable to determine Java version in Travis CI> I'...

# stackoverflow

[user]

Unable to determine Java version in Travis CI
I've been trying to get a Kotlin Spring Boot API to build in Travis CI. I am getting the error:

Could not determine java version from '15.0.2'.

From looking here I tried to update the wrapper version to 6.8.3 (same as system-wide version) and confirmed that it was updated. I still ended up with the same error however. The following is my .travis.yml file.
language: java
install:...