Moving past JDK 1.8

[Lewis John McGibbney]

Hi dev@,
Does anyone have any opinions about moving past JDK1.8?
Maybe JDK1.8 --> JDK11 LTS?

>From what I can see the following files need updated

        modified:   .github/workflows/master-build.yml
        modified:   default.properties
        modified:   ivy/mvn.template

We would also update the Jenkins job configuration(s).

Thanks for any thoughts. 
Best
Lewis