Always invoke gradle wrapper, or not.

[amotl]

Introduction

In order to support projects not including a Gradle wrapper, invoking gradle wrapper was sufficient to create one.
However, this leads to problems on other projects which include a wrapper already, so we removed invoking this command per GH-27.

Problem

Now, we are seeing here, that it indeed leads to problems on projects which would like to generate a new wrapper, because, well, they are running on a newer version of Java where the shipped Gradle wrapper is not compatible with.

The effect is this error message:

BUG! exception in phase 'semantic analysis' in source unit '_BuildScript_' Unsupported class file major version 65

• https://github.com/crate/cratedb-examples/actions/runs/7072688108
• https://github.com/crate/cratedb-examples/actions/runs/7072688109

Thoughts

If we are reverting that change, we could push into a similar direction: Just wipe gradlew and invoke gradle wrapper to generate a new one, which will match the designated Java version. Is it a reasonable idea?

[amotl]

This proposal was implemented with GH-38, and validated on behalf of another CI run on two real-world Java projects.

• ngr: Fix Gradle test runner by wiping existing gradlew Gradle wrapper #38
• Fix running/testing Gradle projects on contemporary versions of Java crate/cratedb-examples#179

/cc @matriv, @seut, @surister, @pilosus