[Backend] Upgrade to Java 16?

[joshmhanson]

Java 17 LTS will be released in September 2021. Should we consider upgrading to Java 16 now so that, if we choose to adopt JDK 17 LTS upon release, we will have already smoothed out any potential issues?

Typically newer JDK versions offer significant performance benefits, but actually the real reason I'm asking is because Java 14-16 add a bunch of cool new language features 😂️

Edit: Per support timelines it looks like free support for JDK 11 (LTS) will end in 2023

[wilsonplau]

This was actually bootstrapped using Java 8, but that's what I thought everyone would have after classes. But if everyone is okay with upgrading and downloading the 16 SDK, I'm onboard as well.