Gradle build cache is not being leveraged

[aloubyansky]

(Following a discussion on Zulip https://quarkusio.zulipchat.com/#narrow/stream/187030-users/topic/Quarkus.20.26.20Kubernetes.20Development.20Environment/near/197398968)
This leads to slower continuous builds.
E.g. the QuarkusBuild gradle task does not declare the output, so no follow-up task can be cached. Quarkus also does not declare any "input" files, which means that the task always runs, even if there is nothing to do.

[quarkusbot]

/cc @quarkusio/devtools

[tobad357]

We run a monorepo.
this would be huge for us. If this works properly we could choose to only generate new docker images for services that have changed when deploying to dev

[glefloch]

@aloubyansky, I would be interested into working on this.

[aloubyansky]

Sure @glefloch go ahead :)