This patch adds the PreviewFeatureInspection inspection that is enabled only when the language level of the project is a preview one. It allows to register warnings and suppress all the preview warnings as it's done in javac. When the language level of the project is not a preview one, HighlightVisitorImpl runs the same visitor that can report errors instead of warnings. It cannot be suppressed.
A PSI element is considered a preview feature when either:
- it is annotated with PreviewFeature directly
- one of its enclosing classes is annotated with PreviewFeature
- its module is annotated with PreviewFeature
It's worth mentioning that when a package in package-info.java is annotated with PreviewFeature this flag doesn't get to be propagated to the classes that are inside the package.
Signed-off-by: Nikita Eshkeev <nikita.eshkeev@jetbrains.com>
GitOrigin-RevId: 5bd22ea2e18ba83303156a2b9665bc54622f6344
