Bump Java version to let CI succeed

[ckittl]

Bump Java version to sth. >= 11

Originally posted by @t-ober in #96 (comment)

[RishiKumarRay]

@ckittl maybe i am wrong but if CI is being built with jenkins the changing def javaVersionId = 'jdk-8' in jenkins file will fix this issue?

[sebastian-peter]

maybe i am wrong but if CI is being built with jenkins the changing def javaVersionId = 'jdk-8' in jenkins file will fix this issue?

Yes, among some other things. You can check out the PR #125 if you're interested