Feat: Suggest Java 1.8 users upgrade JVM via logging

[scottgerring]

Is your feature request related to a problem? Please describe.
It is difficult for the project to get information on usage in different runtimes. It would be useful to start logging an INFO suggesting users upgrade JVM if they are on a very old one and link to some documentation on the powertools site. This way we 1/ can encourage best practices - that is, running a modern Java stack and 2/ start to collect feedback about why users might not want to do that.

Describe the solution you'd like
Log an INFO/WARN suggesting upgrading and linking to our documentation

Describe alternatives you've considered

Additional context

[jeromevdl]

Isn't it too intrusive? abusive?

Isn't WARN too much?

We should log this only during cold start.

How do you see "start to collect feedback about why users might not want to do that." ? By counting the complaints on Twitter and issues raised on GitHub to remove this ?

[AlexeySoshin]

@jeromevdl
I think in the INFO message we could link to the GitHub issue where we say we'd like to deprecate Java 8, and ask users to leave a comment there. WDYT? 🤔

[mriccia]

Is there a way we could print such message at build time, rather than runtime?

My concern with the runtime is the additional logging and the cost/noise that will come as a result.

[jeromevdl]

@mriccia I understand your concern but I don't see how we could do that at build time... we are just a simple dependency, not a maven plugin...
@AlexeySoshin maybe this issue is not the best to start with as we are not yet fully agree how to proceed... and even if we proceed...