Consider Hidden classes use cases

The feature called Hidden classes has been officially marked as a candidate for Java 15 which will reach general availability by the 15 september of this year.

Hidden classes are a feature that is made for framework/libraries that generate classes at runtime.

You have far more expertise than me for considering what could be the use cases/benefits/optimizations that this feature could provide on Jackson, when detecting at runtime that the user supports Java 15.

https://openjdk.java.net/jeps/371

Edit: BTW you could propose, influence the design of the feature while it can still change.