Modular MR project may bypass its own module description

Given a class that is valid in the main source folder based on the corresponding module-info.
If a source folder of a higher version defines a more restrictive module-info, this would probably break at runtime.

Should the compiler re-compile classes take from a lower release against every other module-info?

Start by reproducing the modular multi-release project described, with a class valid against the main source folder's module-info and a more restrictive module-info in a higher-version source folder. Compare the compiler's validation and runtime behavior, then determine whether lower-release classes must be recompiled against each module-info; done means the behavior is corrected or clearly documented.

Written by the indexing model from the issue text.