Occasional contributor and Gradle employee here. Happy to help with any Gradle issues / best practices or find an appropriate person to ask for all pgjdbc build issues.
* Minimal Java: 6 ==> 7 or 8
FWIW Gradle itself requires Java 8 now (though it can build stuff for older JDK versions if required), and has since version 5.0 released in November 2018. My understanding is that we had zero pushback on that, though people could be building older stuff with it. I don't think many are in practice, though our sample may be slanted towards newer / more maintained projects.
How many pgjdbc users still on Java 7 also need the very latest driver features? I bet that number is tiny.
If we do require JDK7 support, I'd strongly recommend building with 8+ so we can use a recent Gradle and then using JDK7 in the build when compiling. I'm happy to assist with that.
* JUnit: 4 => 5
No strong opinion but seems like a no-brainer if upgrading to Java 8.
FWIW we use Groovy and Spock heavily for our testing, which has certain nice features like very readable parameterised tests. But whether introducing a new language to a project is worth it is never just a case of how nice it is.
* Kotlin?
* Other?
Was this suggesting using Kotlin for tests or something else?
