RFR: 8374730: Add support for null restriction in j.l.r.Type

[Maurizio Cimadamore]

On Wed, 7 Jan 2026 16:03:42 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

> This PR adds j.l.r.Type support for null restrictions.
> 
> More specifically, a new public interface is added, namely `NullRestrictedType`, modelling types with null restrictions.
> 
> Changes to the signature parsing code have been made so that instances of the new interface are generated accordingly.
> A new test makes sure that everything behaves correctly.
> 
> Note: we should also make sure that the `AnnotatedType` hierarchy is changed to reflect the null-restriction changes, but for now that is lower priority and will be pursued in a separate PR.

test/langtools/tools/javac/lib/combo/ComboTask.java line 206:

> 204:      * executes them
> 205:      */
> 206:     public void execute(Consumer<ExecutionTask> c) {

I've revived the support to execute test cases from the combo test framework -- we used to have this, but somehow this method got dropped.

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PR Review Comment: https://git.openjdk.org/valhalla/pull/1863#discussion_r2669059837