Consider switching from Reflections to a maintained library

[oliveryasuna]

Describe your motivation

While recently investigating the Gradle plugin, I noticed that the Maven plugin uses the Reflections library to scan the classpath. While I think it would be best to implement something similar to the Gradle plugin (see this issue), if not that, Vaadin should consider switching from Reflections.

Reflections is no longer maintained as of October 2021. Further, it does not support caching, which, if used properly, could greatly speed up the build frontend goal.

Personally, my team and I do not use Maven, and rather use Gradle. However, I imagine many Vaadin users still use Maven and could also benefit from this feature.

Describe the solution you'd like

Vaadin should consider alternative and actively maintained libraries similar to Reflections. Further, it would be beneficial to pick one that supports caching out-of-the-box.

Personally, we use ClassGraph. It is super fast. Not sure if it supports caching, though. The Spring Framework also has ClassPathScanningCandidateComponentProvider, which is very easy to use and very fast.

Additional context

This idea came from our recent endeavour to speed up builds. Relevant issues:

• The vaadinPrepareFrontendTask gradle task is not cached #17941
• Add support for build caching of in-place processed files gradle/gradle#27696
• Include .scss and .sass in stats.json hashes #19527
• Filter classpath scanning for FrontendDependencies #19528
• Document the Gradle plugin's filterClasspath property/closure docs#3477
• Support filterClasspath in Maven plugin, similar to Gradle plugin #19542