Gradle quarkusGenerateCode runs far too often

[FWest98]

Describe the bug

When using Gradle to build a Quarkus app, the quarkusGenerateCode task is almost never cached. Even on successive runs of the same codebase without any code changed, this job will rerun - even on codebases where no code is actually being generated.

I managed to boil it down to the following:

• The task is using cache only when rerunning the exact same configuration; even just running a different unit test (by clicking the gutter in IntelliJ) will cause a rerun.
• Gradle reports that

  Task ':manager:quarkusGenerateCode' is not up-to-date because:
  Value of input property 'cachingRelevantInput' has changed for task ':manager:quarkusGenerateCode'

• When digging into what happens here, I found that both the cachingRelevantInput and internalTaskConfig are often found to be "changed". These values are provided by the task here. These values are provided as a normal map.
• Gradle does not perform a "clever" comparison on these objects (source - the equals call does map-specific things, but will consider map entries as a list and not as a set). In particular, a map with a different order but the same elements is not considered to be equal. Therefore, any change in the order of variables is considered to be a change necessitating a rerun of the job.
  
• Gradle seems to be aware of this and and reports "Other pitfalls can be the use of HashMaps or other data structures without order guarantees in the task’s code." (source) as a potential cause for cache invalidation.

So I think on the Quarkus side, it is best to move to a map implementation that guarantees order of some kind - or find some other way to convince Gradle the task can reuse the cached result. In addition, I feel like the scope of the cachingRelevantInput map is too large: it includes all system properties prefixed by quarkus., even those not affecting code generation at all. It might be good to look into reducing this scope as well.

Output of uname -a or ver

Linux FLORIS-NORTH 4.4.0-22621-Microsoft #3672-Microsoft Fri Jan 01 08:00:00 PST 2016 x86_64 x86_64 x86_64 GNU/Linux

Output of java -version

openjdk version "17.0.10" 2024-01-16

Quarkus version or git rev

3.11

Build tool (ie. output of mvnw --version or gradlew --version)

8.8

[quarkus-bot]

/cc @glefloch, @quarkusio/devtools

[dmlloyd]

I have a possible fix in #41428, could you give it a try?