Support incremental annotation processing with Gradle

[philwebb]

See #16603 for background. The actual fix will be slightly more complex as we'll need to unwrap some Gradle types.

[renjfk]

This is still failing with error Full recompilation is required because '@Override' has source retention. Aggregating annotation processors require class or runtime retention.

[wilkinsona]

@renjfk Thanks for letting us know. I'm not sure I fully understand the connection between @Override and Boot's annotation configuration properties annotation processor. It doesn't look at @Override but I wonder if Gradle's is being confused as the annotation processor declares that it supports all annotation types.

To help us to investigate, can you please open a new issue with a minimal sample that reproduces the behaviour you have described?

[wilkinsona]

With thanks to @ve2m, we now have a new issue and sample: #23580.