Remove JavaVersion in favour of standard Runtime.Version

[reta]

Is your feature request related to a problem? Please describe.
Since JDK-9, the JDK provide standard means to manipulate runtime version using Runtime and Runtime.Version.

Describe the solution you'd like
Remove JavaVersion in favour of standard Runtime.Version

Describe alternatives you've considered
Keep this duplicate hierarchy of classes

Additional context
Since 2.0 set JDK-11 as baseline, we could use Runtime.Version and drop all checks for JDK-8/9/10

[reta]

@nknize it would be good to get it in 2.0, wdyt?